Wattage and percentage tell you almost nothing on their own. UV index at a stated mount distance is the number that decides whether a lamp is right for your animal.
20 pages in this section · how we pick
This is the hub where the hardware decisions live, because they cut across species. One UVB roundup serves all four animals on this site; writing four near-identical versions of it would be filler. What changes between species is the target, not the equipment class.
The Ferguson zone system sorts reptiles by the UV exposure they seek in the wild, and it is the only sensible starting point for choosing a lamp. The published figures, via Northampton Reptile Center and Zen Habitats, run from Zone 1 at a basking maximum of UVI 0.6 to 1.4 up to Zone 4 at 4.5 to 9.5. Your bearded dragon is Zone 3, your ball python Zone 2, and both geckos Zone 1. A lamp that is correct for one is dangerous or useless for another, and no amount of wattage comparison will tell you that.
A 12% T5 HO lamp is not a UVI figure. It becomes one only when combined with a mount distance, a fixture with a reflector, and a correction for how much your mesh blocks. That is why the useful product pages on this site quote distances rather than percentages: an Arcadia Desert 12% at about 11 inches through mesh, a ReptiSun 5.0 at 10 to 14 inches for a snake, a ShadeDweller at 8 to 18 inches depending on output and pigment. Published mesh corrections typically assume a 30 to 45% block. Yours will differ, which is why a meter is the only way to be certain rather than approximately right.
UVB and heat are different jobs and should be different devices. For daytime basking, halogen is preferred because it produces more Infrared-A than ceramic does. For night or ambient heat in a cold room, a lightless source - ceramic emitter or radiant panel - is correct, and a colored night bulb is not, because reptiles see that light.
Every heat source on this site is assumed to be on a thermostat. That is not a preference, it is the difference between a controlled enclosure and a fire and burn risk with an animal inside it. The control type matters: an on/off controller is fine for a lightless emitter or a mat, but it will visibly strobe a halogen lamp, so a light-emitting source needs a dimming or pulse-proportional unit.
Three instruments cover everything on this site. A Solarmeter 6.5 for UV index at the basking surface - and the guidance is explicit that no other device measures reptile UVI accurately. An infrared temperature gun for basking surface temperature, because the published basking figures are surface figures. A probe thermometer and hygrometer for air temperature and humidity in the zone you care about, rather than the stick-on dial gauges sold at the till, which are not accurate enough to trust an animal to.
| Zone 1 - shade dweller | Zone UVI 0 - 0.7, basking max 0.6 - 1.4Leopard gecko, crested gecko |
|---|---|
| Zone 2 - occasional basker | Zone UVI 0.7 - 1.0, basking max 1.1 - 3.0Ball python |
| Zone 3 - open sun basker | Zone UVI 1.0 - 2.6, basking max 2.9 - 7.4Bearded dragon |
| Zone 4 - mid-day sun basker | Zone UVI 2.6 - 3.5, basking max 4.5 - 9.5Uromastyx, chuckwalla |
| Bulb replacement | T5 fluorescent every 12 months, even while still producing visible light |
| Measurement | UVI is measured with a Solarmeter 6.5 or 6.5R. No other device is accepted |
| Fixture rule | No glass or plastic shield over the lamp - both block UVB entirely |
| LED UVB | Reptile lighting researchers consider the technology not yet ready for safe use |
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Best UVB bulbs
UVB bulbs ranked by whether they reach the species UVI target at a distance your enclosure allows.
Top pick: Arcadia T5 HO Desert 12% UVB Lamp
Best T5 fixtures
T5 fixtures judged on reflector performance and whether published distance charts assume them.
Top pick: Arcadia ProT5 Reflector Fixture
Best heat sources
Heat sources ranked by infrared band, thermostat compatibility and the species basking figure they can reach.
Top pick: Exo Terra Intense Basking Spot Lamp
Best thermostats
Thermostats ranked by control type, stated accuracy, load ceiling and whether they alarm on failure.
Top pick: Vivarium Electronics VE-300X2 Dual Proportional Thermostat
Best thermometers
The two instruments that can actually read the published figures: an infrared gun and a probe combo.
Top pick: Zoo Med Digital Thermometer and Humidity Gauge
Best UV meter
What a UV index meter measures, why only the Solarmeter 6.5 class is accepted, and how to use one.
Top pick: Solarmeter Model 6.5 UV Index Meter
Arcadia and Zoo Med UVB compared on published distances, output class and fixture dependence.
UVB 5.0 vs 10.0 decided by Ferguson zone and mount height, not by which number is bigger.
What UVA and UVB each do for a reptile, and why one lamp covers both.
Yes - UVI 4.0-4.5 at the basking surface, with the bulb class and distance to hit it.
Yes, at a low level: UVI 0.5-1.5, and no more than 0.5-0.7 for albino and patternless morphs.
Recommended at UVI 1.0-2.0 at the basking branch, with a specific hatchling caution.
Daily light and UVB hours by species, with the seasonal adjustment for each.
Ferguson zones with published UVI ranges and the mount distance for every lamp class.
The 12-month replacement rule, why visible light misleads, and how to track it.
The three ways a reptile heat lamp causes a fire, and the control for each.
On/off, pulse and dimming control explained, and which heat source each suits.
Why colored night bulbs are wrong, what to use for night heat, and the nightly drop.
What is established about human exposure to reptile UVB lamps, and where the evidence runs out.
How to calculate reptile heating and lighting running costs from your own rate.
Hub
A 4x2x2 is the standard most of the hobby works to. The current published minimum is larger than that. Here is what the numbers actually say, and what to buy once you know them.
Hub
Floor space is the constraint, not height. The published adult minimum is 4.5 sq ft - more than a 20-gallon long gives you.
Hub
The enclosure should be at least as long as the snake. The idea that ball pythons want to be crammed into a small dark box is a myth the published guidance names as one.
Every figure in this section traces to a named source. Where sources disagree, we say so on the page rather than picking quietly - see our editorial policy. Headline references for this hub: Zen Habitats, Northampton Reptile Center.