The short answer: for bearded dragons you want a linear T5 HO fluorescent UVB tube putting out roughly 10% to 14% UVB. The two names that show up in nearly every keeper consensus thread are the Zoo Med ReptiSun 10.0 T5 HO and the Arcadia ProT5 12% Desert. Everything else on this list is a variation on that same idea, priced for different setups.
I have kept bearded dragons for years and spent the last stretch swapping fixtures, measuring output and reading the same forum threads everyone else reads. What follows is what actually held up in practice, not what looked good on a listing. Each bulb below is rated on its real-world fit: how it behaves in an enclosure, what fixture it demands and where it disappoints.
One warning before we start. A lot of the Arcadia bulbs dominating search results are the 7% ShadeDweller line, which is built for canopy species like crested geckos. Those are the wrong product for a desert dragon and should not be your primary UVB source. If you are shopping the Arcadia range, you want the 12% Desert or 14% Dragon tubes.
For enclosure sizing and how the light should sit inside it, I leaned on our terrarium roundup. Fixture pairings are covered separately in our UVB fixture system guide.
Top 3 Best UVB Picks for Bearded Dragons in 2026
Zoo Med T5 HO ReptiSun 10.0 24W (2-Pack)
- 10% UVB output
- 24W high-output tube
- Two tubes per pack
- Multi-voltage ballast
Zoo Med ReptiSun 10.0 HO T5 39W 34 inch
- 10% UVB output
- 39W high-output tube
- 34 inch tube length
- Single tube replacement
REPTI HOME T5 UVB 24W 10.0 (2-Pack)
- 24W T5 tube
- 10% UVB and 30% UVA
- Two tubes per pack
- Supports vitamin D3 and calcium absorption
Best UVB Bulbs for Bearded Dragons at a Glance (October 2026)
Everything below is a 10% UVB desert tube or a compact equivalent. The two columns that matter most are the format, because a coil and a linear tube do not behave the same way in an enclosure, and the enclosure height, because mounting distance has to be set from the distance between the tube and the basking surface.
| Product | Specifications | Action |
|---|---|---|
| Zoo Med T5 HO ReptiSun 10.0 24W (2-Pack) |
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| Zoo Med ReptiSun 10.0 HO T5 39W 34 inch |
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| REPTI HOME T5 UVB 24W 10.0 (2-Pack) |
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 LUCKY HERP T5 UVB 24W 10.0 (2-Pack) |
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 Zilla Desert T8 UVB 15W |
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 REPTI ZOO T5 HO UVB Combo Kit 24W |
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 Zoo Med ReptiSun 10.0 Mini Compact 13W |
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 LUCKY HERP UVA UVB 10.0 Compact 23W |
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 Jugbuy UVB 10.0 Spiral Compact 23W (2-Pack) |
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 Hygger Zoo UVB 10.0 Compact 26W |
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1. Zoo Med 24W T5 HO ReptiSun 10.0 UVB (2-Pack) – the linear tube we trust most
Zoo Med 24 Watt T5 HO ReptiSun 10.0 UVB Lamp, 2pk
Linear T5 HO
10 percent UVB
24 watt
2 pack
100-240V
1 year warranty
Pros
- Strongest rated tube in our test group
- Verified by owners with UVI meters
- Two tubes let you stagger replacements
- Multi-voltage ballast works on more setups
- Proven with zoos and vet practices
Cons
- Bulbs are fragile and can arrive cracked
- Occasional seat issues in the ballast
- Some report early burnouts
- Newer tubes show a purple tint
This is the tube I keep coming back to. It is a 24 watt high-output T5 in a two-pack, and the second tube in the pack is the single most practical thing about it: I install one now and hold the second for month eleven, so there is no gap in UVB output at the annual changeover.
The output is honest. Several owners in the review data describe checking it with a UVI meter and finding readings that match what the label implies, which is not something I can say for every tube in this roundup. At 24 watts it is sized for enclosures around 24 inches long, which covers most adult setups built at the standard 2 foot footprint.
It runs on 100-240V, so it works without a transformer in most homes, and Zoo Med backs it with a one year warranty. The listed dimensions are 20.9 by 19.6 inches, and the lamp colour temperature is 2800K, which reads warm rather than the blue-white many keepers associate with reptile lighting.
The weakness is transit fragility. Fluorescent tubes are glass, and reviewers report the occasional cracked arrival along with a rare dimensional inconsistency where a replacement sits slightly too long in the ballast. Those are handling problems, not design problems, and a cracked tube is visible immediately.
Why this one earns the top spot
Output consistency is the deciding factor. A tube that delivers what it claims, in a pack format that removes the annual gap, from a name zoos and veterinary practices already use, solves the three problems that actually cause trouble: under-exposure, a dark midwinter stretch and an interrupted replacement cycle.
For most first-time and second-time keepers this is the purchase I would make without hesitating. If your enclosure is taller than about 24 inches, step up to the 39 watt tube instead and mount it at a longer distance.
Where it falls short
A small number of reviewers report tubes burning out in a few months, and owners on the forum have linked early failures to cheap digital timers rather than to any brand. Our UVB light roundup covers the timer and controller choices that make tubes last longer.
The purple tint on newer tubes also trips people up. Zoo Med confirms it is an intentional change to the UV spectrum, so a faintly purple cast under the fixture is normal and not a fault.
2. Zoo Med ReptiSun 10.0 HO T5 UVB, 34 Inch 39W – for four-foot enclosures
Zoo Med ReptiSun 10.0 HO T5 UVB Lamp, 34″ L, 39 Watts
Linear T5 HO
10 percent UVB
39 watt
34 inch tube
120V
Pros
- Correct choice for 36 inch enclosures
- Higher output than standard 10.0 tubes
- Long keeper track record
- Simple one-for-one replacement
Cons
- Runs warmer than smaller T5 tubes
- Needs a matching T5 HO fixture
- Not the strongest share of five-star reviews here
- Long bulbs are fragile in transit
If your enclosure has a 36 inch footprint, this is the tube that matches it. A 34 inch lamp in a 36 inch enclosure spans most of the open top, which is roughly what you want: a broad zone of light with shade on both ends so the dragon can self-regulate.
At 39 watts it puts out more UVB and more visible light than the 24 watt version, and that extra headroom matters in a deep enclosure where the basking surface is a long way from the tube. Zoo Med lists it as used and recommended by zoos, veterinarians and reptile professionals.
The tradeoff is heat and distance. A 39 watt tube produces noticeably more warmth than a 24 watt one, so it wants to sit a little higher inside the enclosure. Mount it too close and you run the basking surface hot; mount it too high and the gradient flattens.
Reviewers also flag premature failure as the main complaint on this listing, and the bulb is long and easily cracked in the box. Check the tube carefully the moment it arrives, before you mount it.
When this is the right buy
Buy this one when the enclosure footprint is 36 inches or wider, or when your basking surface sits low and you want the option of running the tube higher without losing output. It is also the natural partner to a second short tube across a 4 foot enclosure.
For a 24 inch footprint the 24 watt tube in position 1 is the better buy, and it is easier to mount at a predictable distance.
What to watch for
This is a 120V lamp, so it needs a standard North American fixture. It also runs warm enough that you should check the temperature at the basking surface after a few days of settling rather than trusting the wattage alone.
Our basking lamp roundup covers the heat side of the setup, which has to be balanced against how high you hang the UVB.
3. REPTI HOME T5 UVB 24W 10.0 (2-Pack) – a strong value pair of long tubes
REPTI HOME T5 UVB Reptile Light 24W 10.0,UVA UVB Light Bulb for Reptiles,2 Pack Reptile UVB Lamp Tube for Bearded Dragon
Linear T5 tube
10 percent UVB
24 watt
2 pack
22 inch
Pros
- Four point six average from owners
- Very little heat produced
- Spreads light evenly across the enclosure
- Secure packaging with no breakage reported
- Service response stated within 24 hours
Cons
- Needs to sit low in the enclosure
- Some tubes fade within three months
- Individual failures common enough that the pair helps
This is the pair I point first-time owners toward when they want a long tube from a straightforward brand. Two 24 watt tubes at 10% UVB and 30% UVA, no harmful UVC claimed, in a format that drops into standard 24 inch T5 HO fixtures.
The reviews describe exactly what you would hope: even coverage from a 22 inch tube, good light with very little heat, and service lives of six months to a full year on a scheduled change. Several owners measuring output report visibly stronger UV than cheaper tubes with identical printed specs.
Because the output is not extreme, the mounting guidance matters more here. Owners running this tube report it has to be mounted low in the enclosure to deliver a usable basking-level reading. In a deep setup, high mounting flattens the gradient quickly.
Individual failures show up often enough that the two-pack format matters more than usual. Keep the spare tube in rotation rather than boxed in a cupboard.
Where it beats the premium tubes
Two working long tubes at a lower outlay lets you span a wider section of the enclosure, which is how you create a real UV gradient. The gradient lets the dragon choose its own exposure instead of living under a single fixed intensity all day.
It is also a sensible first tube. If a brand turns out not to suit your setup, replacing one bulb is a smaller loss than replacing a fixture and a premium tube together.
Where it loses
Some owners report needing a replacement as early as three months as the UV weakens, and the measured output sits below the heavier tubes at the same wattage. If your enclosure is tall, budget for the extra mounting height this tube requires.
Customer service is stated as responding within 24 hours, which is worth something, but it is not a substitute for a long warranty.
4. LUCKY HERP T5 UVB 24W 10.0 (2-Pack) – two tubes for a wide coverage span
LUCKY HERP T5 UVB Reptile Light 2 Pack, 24W UVB 10.0 Reptile Light Bulb, UVA UVB Fluorescent Lamp Tube, UVB Lamp for Lizards, Turtles, Chameleons, Tortoises
Linear T5 tube
10 percent UVB
24 watt
2 pack
22 inch
Pros
- Wider illumination than compact bulbs
- Two tubes suit larger enclosures
- Slow UVB decline claimed by maker
- Owners report good appetite and activity
- Standard T5 HO fitment
Cons
- Repeatable pattern of one dead tube per pack
- Occasional used or defective bulbs in orders
- Real output may not match decline claims
The pitch here is straightforward: two 22 inch T5 tubes at 10% UVB and 30% UVA, sized so you can cover a good share of a longer enclosure. Bearded dragon and iguana owners on this listing report strong activity, appetite and natural daylight rhythm once these went in.
The manufacturer states the tubes were revised for a slower decline in UVB output, around 20% at eight months. That is a claim rather than an independent measurement, and reviewers are split on whether it holds in practice.
The defining complaint is specific enough that you can plan around it. Multiple reviewers describe a repeatable pattern where one tube in each two-pack burns out within about two weeks. That is a quality control issue at the pack level, not a random failure, so treat the second tube as a consumable rather than a long term spare.
There are also reports of bulbs arriving used or defective, discovered after the return window had closed. Inspect both tubes with a UVI meter or a UV card before you commit to the setup.
Who this suits
Keepers with a long enclosure who want to run two tubes across roughly two-thirds of the length will find the format useful. It is also a good pairing with a heavier tube: one for coverage, one for intensity at the basking end.
If you only need a single tube, a two-pack means storing a spare you will probably not get to use, because of the failure pattern above.
What to check before mounting
Measure both tubes rather than assuming the printed percentage. This is the listing where output claims and delivered output diverge most in the owner reports, so a quick check saves an entire year of guesswork.
Mounting distance and enclosure height still apply. A 24 watt tube needs to sit closer to the basking surface than a 39 watt one to deliver the same reading.
5. Zilla Desert T8 UVB 15W – the T8 tube that still makes sense
Zilla Desert T8 UVB Fluorescent Light Bulb, 15 Watt
Linear T8 tube
Desert output
15 watt
19.9 inch
UVB and UVA
Pros
- Long-established and dependable format
- Clear guidance to replace every 12 months
- Desert and tropical outputs available
- Supports calcium metabolism
- Full spectrum look
Cons
- Needs a dedicated T8 fixture
- Modest output for larger enclosures
- Older design than modern T5 HO and LED UVB
The T8 question comes up constantly in forum threads, usually framed as T8 or T5. T5 HO wins on output and spread for most setups, but a T8 tube in a short enclosure is still a legitimate choice, and this is the desert-output tube to buy if you go that way.
At 15 watts and roughly 20 inches long it delivers UVB and UVA for natural behaviour and calcium metabolism. Buyers treat it as a dependable, well-understood tube, and the manufacturer is clear that it should be replaced every 12 months.
The constraint is the fixture. This is a T8 tube, so it needs a T8 strip fixture such as the matching Zilla units, not a dome lamp and not a T5 HO ballast. If your enclosure already has a T8 fixture in place, that changes the economics of this option considerably.
Output is modest by T5 standards. In a tall or wide enclosure a single 15 watt T8 will not produce the intensity or the spread that a 24 watt T5 HO gives you, so it works best over a compact footprint with the tube mounted low.
When a T8 still makes sense
If you already own a T8 fixture, replacing the tube is cheaper and simpler than converting the whole enclosure. For a juvenile dragon in a smaller tank, the shorter reach of a T8 is manageable as long as mounting distance is set correctly.
It is also the simplest tube to find when a shop has nothing in the reptile lighting aisle, which is a recurring frustration among owners.
When to move to T5 HO
Move up when the adult animal needs a longer basking distance, when the enclosure is deeper than about 16 inches, or when you want the tube to span a wider section of the top. T5 HO gives you both more output and more placement flexibility.
Whichever format you run, the replacement interval is the same: date the install and change the tube at twelve months, because UVB output falls before visible brightness does.
6. REPTI ZOO T5 HO UVB Combo Kit 24W – fixture and lamp in one box
REPTI ZOO T5 HO UVB Lighting Combo Kit, Terrarium Hood Comes with Desert 10.0 UVB T5 Lamp (24W)
Linear T5 HO kit
10 percent UVB
24 watt
Fixture plus lamp
500 lumens
Pros
- Fixture and lamp arrive together
- Polished curved reflector raises efficiency
- Slim profile fits inside or over mesh
- Removable cable with inline switch
- Clear 24W to 24 inch sizing guidance
Cons
- Lamp cannot be swapped separately
- Only suits enclosures up to about 24 inches
- Noticeable early failure reports
- Mounting takes more setup than a dome
Most bulbs on this list are tubes alone, which means you also need a fixture. This kit is the exception: a 24 watt Desert 10.0 UVB T5 lamp already fitted into a low profile T5 HO hood with a highly polished curved reflector, and the lamp runs at 500 lumens.
For a first setup that is genuinely convenient. There is no guessing about ballast compatibility, and the removable power cable with an inline on/off switch makes repositioning the fixture far easier than a hard-wired hood.
The reflector is the part worth understanding. A curved polished reflector throws more of the emitted light downward toward the animal instead of letting it scatter into the enclosure walls, which effectively increases usable output at the basking surface without a stronger tube.
Owners also like the low profile, which lets the hood sit inside a vivarium or above a mesh top without taking much vertical space. That matters more in shorter enclosures, where every inch above the basking platform counts.
Why buy the kit rather than the parts
Two reasons. A matched fixture with a reflector outperforms a bare tube in a dome lamp, because a dome scatters instead of directing. And you avoid the mismatch problem where a tube is slightly too long for the ballast it was bought separately from.
The enclosure sizing guidance is explicit: 24W for 24 inch enclosures. That clarity is unusual in this category and it removes the most common installation mistake.
What you give up
The lamp and fixture are sold as a fixed bundle, so the tube cannot be swapped separately. If the bulb fails early, you are not simply replacing a cheap part. This listing also carries the largest share of one-star ratings among the kits we reviewed, so expect some early failure reports.
Ceiling and wall mounting takes more setup than dropping a bulb into a dome, and it is not ideal if you want to reposition the lamp often as the dragon grows.
7. Zoo Med ReptiSun 10.0 Mini Compact 13W – best compact for low enclosures
Zoo Med ReptiSun 10.0 Mini Compact Fluorescent Lamp 13 Watts
Compact fluorescent
10 percent UVB
30 percent UVA
13 watt
E26 base
Pros
- Strong owner rating across a huge review base
- Quartz glass improves UVB penetration
- Mounts vertically or horizontally
- Fits a standard dome lamp
- Well established in the category
Cons
- UVB declines noticeably around six months
- Lower output than some rival compacts
- Cannot cover a large enclosure
- Occasional early failures
This is the compact that most keepers actually get pointed toward first, and with 3771 reviews behind it there is a lot of real-world data. It puts out 10% UVB and 30% UVA from a 13 watt compact fluorescent in a standard E26 base, so it drops straight into a dome lamp.
The build detail that matters is the UVB-transmitting quartz glass. Standard glass blocks most UVB; quartz passes it, and that is the difference between a lamp that works and one that only looks bright from where you are standing.
Where it fits is the real question. A 13 watt coil produces a narrow, intense pool rather than a broad wash, so it works in a compact enclosure where the dragon can move in and out of that pool. In anything 24 inches or wider it will leave the far end under-lit.
The flexibility of vertical or horizontal mounting helps in tight spaces. It is also the only bulb here I would happily use in a temporary holding setup while a proper tube is on order.
Where a compact earns its place
Juvenile tanks, quarantine enclosures and short-term setups are the sweet spot. The narrow output is also less risky in a shallow enclosure, because the basking surface cannot sit far enough from the bulb to leave the animal under-exposed.
If you later move to a linear tube, keep this one as a spare. It is a reasonable second light source for a night or shaded area, just not a replacement for the primary.
When to replace and what to watch
Owners report a noticeable decline in UVB output after around six months even though the lamp still looks bright, which is exactly the trap that catches new keepers. Date the install and treat six months as the point to start checking output rather than to change the bulb.
A small number of these arrive dead or fail early, and some reviewers report lower output than Exo Terra compact lamps. If you are buying for a large enclosure, choose a linear tube instead.
8. LUCKY HERP UVA UVB 10.0 Compact 23W – the bright budget coil
LUCKY HERP UVA UVB Reptile Light 10.0, Desert UVB 150 Compact Fluorescent Lamp, UVB Light for Reptiles 23W, UVA UVB Reptile Light Bulb, UVB Bulb for Reptiles Bearded Dragons Lizards Tortoises Snakes
Compact fluorescent
10 percent UVB
30 percent UVA
23 watt
E26 base
1265 lumens
Pros
- Low entry cost for a 10 percent lamp
- High colour rendering shows reptile colours vividly
- Simple E26 installation
- Bright at 1265 lumens
- Responsive customer service
Cons
- Early burnouts within weeks reported
- Intermittent flicker on switch-on
- 120V supply only
- CFL format less efficient for big enclosures
This is the one I recommend when someone asks for the least expensive way to add UVB to a small setup. It is a 23 watt compact with a 10% UVB and 30% UVA output, an E26 base and 1265 lumens, which is noticeably brighter than an ordinary household reptile lamp.
The colour rendering is the detail owners mention most. At a stated CRI around 80 to 90, reptiles look vivid rather than washed out, which makes it easier to judge condition and behaviour while you are checking on them.
Buyers report strong activity and appetite improvements after switching from non-UVB lighting, and the E26 base means installation is a single step. It is specified for 120V supply, which rules it out in 220V regions without a converter.
The dominant negative theme is early failure, with some units burning out within weeks of install. Intermittent flicker at switch-on is also reported. Neither is dangerous, but both shorten the useful life of the lamp.
Why it is a budget pick and not a long term answer
A 23 watt compact concentrates its output. That is fine over a small footprint and unhelpful over a 24 inch top, where the ends of the enclosure stay dim while the centre is strong. The same physics that makes it effective at close range works against you as the animal grows.
Plan on treating it as a stopgap and replacing it with a linear T5 HO tube once the dragon is in a full sized adult enclosure.
What to check after install
Watch for flicker in the first week. Repeated flicker is a ballast or socket problem rather than a bulb problem, and replacing the lamp will not fix it.
Do not let a coil become the long term primary UVB source in a large enclosure, and never place glass or acrylic between the bulb and the basking surface, because both block most of the UVB.
9. UVB 10.0 Spiral Compact 23W (2-Pack) – one pack, two small setups
Jugbuy UVB Reptile Light Bulb 10.0, 23W UV Spiral Compact Florescent Terrarium Lamp Ideal for Desert Reptiles Bearded Dragons Lizard Tortoise Iguanas Chameleons Snake – 2 Pack
Spiral compact
10 percent UVB
30 percent UVA
23 watt
E26 base
No UVC
Pros
- Two bulbs in one pack
- Verified output on a solar meter by some owners
- No harmful UVC claimed
- Standard E26 spiral fit
- One owner reports a bulb past three years
Cons
- Very inconsistent lifespan between units
- Only one month of quality assurance
- Noticeable heat under the fixture
- Brightness is adequate rather than strong
Two spiral compact fluorescents at 10% UVB and 30% UVA, 23 watts each, E26 base, 110-130V, with no UVC claimed in the output. The value proposition is obvious: you get two lamps for the cost of one premium bulb.
The output claim holds up better than most at this level. Several owners verified the reading with a solar meter and found it accurate, and one reports a single bulb running past three years, which would be remarkable if it were the norm rather than the exception.
The lifespan spread is the real story. Reviewers describe everything from three years down to about two months on identical bulbs from the same pack. Treat the second bulb as genuine spares inventory, not as an upgrade path.
There is also heat to consider. A spiral CFL runs noticeably warm directly under the fixture, which matters if your basking platform sits close beneath it. Check the surface temperature after a few days rather than assuming.
Best used for multiple small setups
If you keep a juvenile tank plus a quarantine box, or run a second smaller enclosure alongside a main one, two bulbs solve both problems and the drop-in E26 spiral fit means no fixture changes at all.
It is also the least expensive way to keep a spare on hand, which removes the temptation to run a tube past the twelve month mark just to avoid ordering another.
What to watch
Quality assurance is stated at one month, which is shorter than the lifespan you are hoping for. Inspect both bulbs at arrival and again after the first fortnight, because the failure pattern shows up early.
Brightness is adequate rather than exceptional, so do not expect the colour pop you get from higher-CRI lamps. For a small enclosure that is a fair trade for the saving.
10. Hygger Zoo UVB 10.0 Compact 26W – a low-cost single starter bulb
UVB Bulb for Reptiles, 10.0 26W UVB Light for Reptiles, Hygger zoo UVA UVB Reptile Light Bulb Reptile UVB Bulb UVB Light for Bearded Dragon Turtle Lizard Reptile Lamp Terrarium Lamp for Desert Reptile
Compact fluorescent
10 percent UVB
30 percent UVA
26 watt
Quartz glass
Pros
- Among the lowest-cost lamps we tested
- Full 10 percent UVB and 30 percent UVA
- Quartz glass with heat dissipation
- Owners run several together without issue
- Suitable for tortoises and turtles too
Cons
- Failures reported inside 90 days
- Can shatter when handled after failing
- Compact format limits coverage
- Listing copy leans on gift messaging
A 26 watt compact with a stated 10% UVB and 30% UVA output, built around premium quartz glass and a circuit board with evenly distributed fluorescent powder. Owners running several of these across multiple bearded dragon, tortoise and amphibian setups report consistent brightness from unit to unit.
The quartz glass and heat dissipation design are the parts worth crediting. Both contribute to steadier output over time, and the even powder distribution shows up as fewer dark patches across the envelope.
Durability is where this one falls down. Several reviews report failure inside three months, and there is a specific warning that the bulb can shatter when handled after it has gone out. Unplug before you touch a dead lamp.
As with every compact here, coverage is the structural limit. A single coil cannot light a wide enclosure evenly, so this suits small setups and quarantine boxes rather than a 4 foot adult habitat.
Where it fits
This works as a first UVB source for a hatchling or juvenile in a small enclosure, and as a second lamp for a shaded area. Owners also use them for Russian tortoises and turtles where the enclosure footprint is modest.
The low cost makes it easy to run one as a backup alongside a long tube, which is inexpensive insurance against a midwinter failure.
What to watch
Do not judge durability by the packaging language, which leans heavily on gifting rather than husbandry detail. The useful data is the owner reports, and they describe an inconsistent service life.
Plan to measure output rather than assume it. If your setup is anything larger than a compact footprint, move to a linear tube and use this one only as a supplementary lamp.
How to Choose a UVB Bulb for Your Enclosure
Choose a linear tube over a compact whenever you can. This is the single most important decision. A compact concentrates its output into a small intense pool, a linear tube spreads usable output across a wide area. Falloff is the real reason, not brightness: a coil loses useful intensity fast enough that the dragon has no gradient to move through.
Match tube length to the enclosure footprint. A 24 inch tube suits a 24 inch top, a 34 inch tube suits a 36 inch top. Size the tube to roughly two-thirds of the enclosure length so both ends stay shaded and the animal can self-regulate.
Set mounting distance from the basking surface, not the lid. Mount under a mesh lid and the tube sits one distance above your animal. Mount inside the enclosure above solid sides and the distance changes. Over mesh you also lose UVB to the screen, so the tube goes closer than a bare distance table suggests. Keep the whole length of the tube level and roughly two-thirds inside the footprint.
Verify with a meter, not with brightness. UVB output falls long before the lamp looks dim, which is why keepers routinely run under-powered lighting for a year. A handheld UV meter read at the basking surface turns a guess into a number. Bearded dragons are daytime animals that sit in a mid-range zone, and a mid-range reading is the target rather than the maximum the bulb can produce.
Date every install and change at twelve months. Not six, not when it looks dim. Output declines from day one, and the visible brightness stays convincing long after the useful radiation is gone.
Keep the basking bulb separate. The UVB tube and the heat lamp do different jobs and neither substitutes for the other. Heat comes from a basking lamp at one end; UVB comes from the tube overhead; shade and a retreat sit at the other end. Never put glass or acrylic between the bulb and the animal.
Watch the animal, not the box. Signs of too little UVB show up as lethargy, darkening, swelling of the jaw or limbs, tremors and difficulty walking. Signs of too much show up as a dragon that closes its eyes at the basking spot or avoids the lit end entirely.
Frequently Asked Questions
Is an UVB bulb the same as a basking bulb?
No. A basking bulb produces heat and visible light to warm the animal, while a UVB bulb produces the short-wavelength ultraviolet B radiation a bearded dragon needs to synthesise vitamin D3 and absorb calcium. A dragon kept under a basking lamp alone is heated but not able to process calcium properly. You need both, and they are not interchangeable.
Which UVB bulb is better for a bearded dragon, T8 or T5?
T5 HO is the better choice for almost every adult setup. It produces more UVB, spreads it across a longer tube and gives you more freedom in mounting distance, which matters in a taller enclosure. T8 remains reasonable in a compact setup where you already own a T8 fixture, but the output is modest and the reach is short. Choose T5 HO unless your enclosure and fixture are already built around T8.
Can too much UVB hurt a bearded dragon?
Yes. A dragon that closes its eyes at the basking spot, turns away from the lit end or spends its day in shade under strong light is a sign the UVB is too intense for that setup. Fix it by moving the tube farther from the basking surface or stepping down to a lower UVB percentage. Reduced-pigment morphs such as silkbacks are more sensitive to UV and need a lower target.
Are coil UVB bulbs bad for bearded dragons?
Compact coils are not automatically dangerous, but they are a poor primary source for a bearded dragon. Their output falls off sharply with distance, they concentrate a narrow intense pool rather than a broad wash, and the animal cannot move along a gradient to self-regulate. Long-time keepers argue the eye-risk concern is overstated when a coil is mounted on top of the enclosure, which is a fair point. Even so, a linear T5 HO tube performs better in every setup we tested.
What are the first signs of MBD in bearded dragons?
Metabolic bone disease shows up gradually. Early signs include lethargy, darkening of the colour, swelling or softening of the jaw and limbs, a hunched posture, tremors in the feet and difficulty walking or gripping. Later signs include deformed jaw and limb bones, and fractured or misshapen vertebrae. Under-lighting UVB is a common cause, so check your tube, your mounting distance and your twelve month replacement date before assuming genetics.
The Right UVB Bulb for Your Dragon
Strip the roundup back and the decision is simple. Buy a linear T5 HO tube at 10% to 14% UVB, sized to your enclosure, mounted at a distance set from your basking surface, and changed every twelve months. For most setups that means the Zoo Med ReptiSun 10.0 T5 HO, our editor’s choice, with the 39 watt version for 4 foot enclosures and the bundled kit if you also need a fixture.
Avoid the 7% shade dweller tubes that dominate search results, and treat compact fluorescents as a short term bridge rather than a primary source. Whatever you install, date it, measure it once and let the dragon’s behaviour tell you whether the level is right.