Best UVB Light for Bearded Dragons: Why Output Spec Is the Only Number That Matters
Choosing the best UVB light for a bearded dragon is not about price or brand loyalty. It is about delivering a UVI (UV Index) of 4-6 at the basking perch surface.
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Before picking any bulb, read the published Ferguson Zone data for reptiles in the wild.
Pogona vitticeps occupies Ferguson Zone 4 in its native Australian scrubland, experiencing peak UVI of 4.5-7.0 during basking. Any bulb that cannot achieve at least UVI 4 at 12 inches is undersized for this species.
| Bulb | Type | Output % | UVI at 12" | Lifespan | Price |
|---|---|---|---|---|---|
| Arcadia Dragon 14% T5 HO | T5 HO fluorescent | 14% | 5.8-7.2 | 12 months | $40-$55 |
| Zoo Med Reptisun 10.0 T5 HO | T5 HO fluorescent | 10% | 4.0-5.5 | 12 months | $25-$40 |
| Arcadia 12% T5 HO | T5 HO fluorescent | 12% | 4.8-6.0 | 12 months | $35-$50 |
| Exo Terra Intense Basking 200W MVB | Mercury vapor bulb | Combined UVB+heat | 5.0-8.0 | 12-18 months | $60-$90 |
| Zoo Med Powersun 100W MVB | Mercury vapor bulb | Combined UVB+heat | 4.5-7.0 | 12-18 months | $55-$75 |
Arcadia Dragon 14% T5 HO: Best Overall UVB Bulb for Bearded Dragons
The Arcadia Dragon 14% T5 HO was designed specifically for Ferguson Zone 3-4 species, covering the full UVB exposure that this species requires. It produces UVI 5.8-7.2 at 12 inches with a reflector, which exceeds the minimum requirement and gives real margin for keeper error.
Arcadia publishes independent Solarmeter test data for each bulb size, which is a transparency standard no other brand matches consistently.
- Output: UVI 5.8-7.2 at 12 inches with reflector
- Ferguson Zone match: Zone 4 (correct for bearded dragons)
- Lifespan: 12 months before output degrades below spec
- Sizes available: 24", 36", 46", 54"
- Requires: T5 HO fixture with reflector hood
Zoo Med Reptisun 10.0 T5 HO: Best Budget UVB Bulb for Bearded Dragons
The Zoo Med Reptisun 10.0 T5 HO has been the industry standard for bearded dragon UVB since T5 HO fixtures became common around 2015. It produces UVI 4.0-5.5 at 12 inches with a reflector, which meets the minimum spec for Pogona vitticeps.
The Reptisun 10.0 T5 HO is widely stocked at PetSmart, Petco, and Amazon, making replacement simple. Its lower output compared to the Arcadia 14% means it must be mounted no more than 10-12 inches above the basking surface. A full enclosure positioning guide covers fixture height in detail.
- Output: UVI 4.0-5.5 at 12 inches with reflector
- Availability: PetSmart, Petco, Amazon, reptile shops
- Price range: $25-$40 per bulb
- Sizes available: 18", 24", 36", 46"
Arcadia 12% T5 HO: The Middle-Ground Option
The Arcadia 12% T5 HO sits between the Dragon 14% and the Reptisun 10.0 in output and price. It produces UVI 4.8-6.0 at 12 inches and is the most common recommendation in UK bearded dragon communities.
If you already own an Arcadia fixture from another species, the 12% bulb is the easiest upgrade path for a bearded dragon enclosure. Keepers deciding between two popular lizards can find a side-by-side lighting and husbandry breakdown in the bearded dragon vs leopard gecko comparison before committing to a fixture.
Mercury Vapor Bulbs for Bearded Dragons: One Lamp Does Both Jobs
Mercury vapor bulbs (MVBs) combine a basking heat source with UVB output in a single lamp. The Exo Terra Solar Glo and Zoo Med Powersun are the two most commonly used options.
MVBs work best in large enclosures where the basking spot can be at least 14-18 inches below the lamp. At shorter distances, the heat output becomes too intense even as UVB remains correct.
Do not use MVBs in enclosures smaller than 4x2x2 feet. Species like the leopard gecko never require MVBs given their lower UVB needs and belly-heat preference.
UVB Bulb Placement: Screen Tops Block 40% of Output
Screen mesh reduces UVB output by 30-40%, which drops a Reptisun 10.0 from UVI 4.5 to approximately UVI 2.7 at the basking surface. This is insufficient for bearded dragons.
Mount the T5 HO fixture inside the enclosure or remove the screen section directly below the fixture. A bulb mounted inside with no screen between it and the animal delivers its full rated output. The same inside-mount principle benefits the crested gecko, though its UVB demands are far lower.
- Inside mount (ideal): Full rated UVI output, no screen blocking
- On top of screen: 30-40% output loss, may fall below UVI 4 threshold
- Correct distance: 8-12 inches from basking perch to bulb for T5 HO 10-14%
- Replacement schedule: Every 12 months regardless of visible light output
The blue-tongue skink also occupies Ferguson Zone 3-4, making it the closest parallel species for UVB bulb selection among common pet lizards.
High-demand species like the chameleon require similar UVI levels but in very different enclosure configurations that affect bulb placement entirely.
Low-UVB colubrids like the corn snake and the ball python do not require the T5 HO intensity this guide covers.
Semi-aquatic species such as the red-eared slider use UVB over basking platforms rather than a perch, making screen placement less of a concern.
Unlike Ferguson Zone 4 obligates, the king snake thrives on standard-output UVB and has no requirement for the T5 HO intensity this guide covers.