Best UVB for a Leopard Gecko (Do They Need It, and Which Bulb)

Do leopard geckos need UVB?

They strongly benefit from it, and modern keepers treat it as recommended rather than optional. Leopard geckos are cryptic baskers. They don't sunbathe in the open like a bearded dragon, but they do absorb ambient UV at dawn and dusk, and that UV lets them make their own vitamin D3 to use calcium properly and avoid metabolic bone disease. As keepers put it, supplements don't fully replace UV, because a gecko doesn't absorb most dietary D3 through its gut the way it uses D3 made in the skin.

You can keep a leopard gecko on dietary D3 alone, and plenty of healthy geckos have been raised that way, which is why older advice says "not strictly necessary." UVB is the more natural and forgiving route, it's inexpensive, and it takes the guesswork out of D3 dosing. Unless you have a specific reason not to (see the note on albinos below), add it.

How much: low UVB, and distance is everything

Leopard geckos need low UV. On the Ferguson zone scale used for reptile lighting they're zone 1, the shade-dweller end, so you're aiming for a low reading at the basking spot rather than the strong output a desert basker wants. Buying a high-output bulb meant for a bearded dragon is the most common way people over-do it.

The number on the bulb is only half the story, though, because what reaches the gecko depends on distance and whether a mesh screen sits in between. As one keeper put it, "it's impossible to know if it's too strong without knowing if you have mesh in between and the distance. The weakest UVB available would be dangerous at 4 inches but the strongest would be totally fine at 3 feet." Look up a leopard gecko UVB (Ferguson zone) chart, mount the bulb at the distance it specifies, over your mesh, and you're set. A moderate bulb at a sensible distance is safer than a weak one held too close.

T5 linear, never coil (and ReptiSun is not Reptizoo)

Buy a T5 HO linear tube. The old coil and compact UVB bulbs are out: keepers are blunt that "the coil UV bulbs and compact aren't good to use anyway," and they've been linked to eye problems and unreliable output. You want a flat linear tube spread across part of the enclosure.

Two brand-name traps. The two UV brands keepers recommend are Zoo Med's ReptiSun and Arcadia, and ReptiSun is not Reptizoo, a different company with a similar name. A keeper flags this exact mix-up. Then, if you go Arcadia, buy the plain ShadeDweller bulb rather than the pricier LumenIZE dimming kit (more on that below). Match the fixture length to your tank: a 36-inch fixture suits a standard 40-gallon.

ReptiSun 5.0 vs Arcadia ShadeDweller

These are the two low-UV options keepers name, and either one works. The Arcadia ShadeDweller is the gentle, leo-specific favorite ("their shade dweller bulb is top notch"), but it has been chronically sold out: keepers report it unavailable "everywhere, PetSmart, Reptile Basics, Dubia," partly from panic-buying over an unrelated bulb-ban rumor. T5 UV tubes are not banned. Arcadia sells it direct rather than on Amazon, so plan to buy from them.

The Zoo Med ReptiSun 5.0 T5 HO is the buyable everyday standard, and usually cheaper. It's a touch stronger than a ShadeDweller, which is why distance matters: mounted the correct distance above the basking spot over mesh, a 5.0 suits a leopard gecko. Skip the Arcadia LumenIZE ProT5 dimming kit. Keepers report short bulb life and "weird noises," and the "slow ramp" sunrise effect is widely called a gimmick. A leopard gecko doesn't need dimming UVB, and dimming appears to shorten bulb life.

Mounting, timers, and replacing it

• Distance over mesh: mount the tube above the mesh at the distance your Ferguson-zone chart specifies for that bulb, above the warm/basking end, so the gecko can move into and out of the UV.
• Timer, not dimmer: put it on a plain on/off timer with the rest of your lights. UVB doesn't need dimming (that's for heat bulbs on a thermostat), and dimming it can shorten bulb life. Keepers running theirs on a simple timer report no bulb problems.
• Replace it yearly: a UV tube keeps making visible light long after its UV output has faded, so swap it about once a year even if it still lights. A UV meter tells you when output drops if you want to be precise; otherwise mark the date and replace on schedule.

A note on albinos

Albino leopard geckos and other light-sensitive morphs have less pigment and can be bothered by bright overhead light. Some keepers skip UVB for them and rely on dietary D3 instead, which is a legitimate choice. It isn't automatic, though. Plenty of keepers run UVB with albinos by keeping it low and giving the gecko dense clutter and shaded hides so it can always get out of the light. If you have an albino, provide the cover first, then decide.

With UVB, adjust your calcium

Adding UVB changes your supplement routine. Without UV, you dust heavily with a D3 calcium so the gecko gets its vitamin D from food. With UV, the gecko makes its own D3, so you switch to a low-D3 (or no-D3) calcium to avoid overdosing, plus a multivitamin. An all-in-one low-D3 product covers it in one step. Sort the enclosure and heating alongside the lighting and the setup is close to done.

What we'd buy

Low UVB from a T5 HO linear tube, never a coil, either a Zoo Med ReptiSun 5.0 or an Arcadia ShadeDweller, mounted at the distance a Ferguson-zone chart specifies over your mesh. Run it on a timer rather than a dimmer and replace it yearly. Switch to a low-D3 calcium now that the gecko makes its own. Avoid the coil bulbs, the over-strong desert bulbs, and the dimming kit.