# Reptile heat lamp wattage calculator

> Set your species, enclosure height, and room temperature to estimate a starting heat lamp wattage, rounded to standard 40/90/100 W halogen steps. The result is an evidence-based starting point, not a precise value, so verify actual temperatures with a thermostat.

## Who stands behind this calculator

Written by [Patrick Li](/authors/patrick-li/). Editorially reviewed 2026-09-01 · Evidence checked 2026-09-01.

Evidence: Multiple sources agree · Evidence from this species.

The calculator estimates a starting bulb wattage from enclosure height, room temperature, and the selected species’ target temperatures. It does not regulate anything — a thermostat must always control the heat source — and it does not replace the species’ full basking and temperature-gradient requirements.

## Direct answer

Most reptiles do fine starting with a 40–100 W halogen flood sized to species, enclosure height, and room temperature. A bearded dragon in a 24-inch-high enclosure estimates 100 W per bulb, a ball python in an 18-inch-high enclosure 90 W. Treat either as a starting point and verify with a thermostat probe.

## Recommended setup

Use the interactive calculator on the page: https://petguidecalc.com/reptile/heating-wattage-calculator/ — pick a species, enter the enclosure height and room temperature, and get a starting wattage rounded to the standard 40/90/100 W halogen steps.

## Species heating starting points

| Species | Scientific name | Starting wattage (reference height) | Note |
|---|---|---|---|
| Bearded dragon | Pogona vitticeps | 100 W (24 in) | About a cluster of 2× 90–100W halogen flood bulbs in a 24-inch-high enclosure, on a thermostat. |
| Ball python | Python regius | 90 W (18 in) | About a cluster of 2× 90W halogen floods for a 4×2×2 ft enclosure, on a thermostat. |
| Crested gecko | Correlophus ciliatus | 40 W (24 in) | About a 40W incandescent or low-wattage halogen in a 24-inch-high enclosure. |

## How the estimate is calculated

ReptiFiles states that no single wattage works for every reptile, so this calculator starts from each species’ published starting point: a bearded dragon in a 24-inch-high enclosure needs about 2× 90–100 W halogen floods, a ball python in a 4×2×2 ft enclosure about 2× 90 W, and a crested gecko about 40 W.

The estimate scales that starting wattage by enclosure volume (footprint × height) and by room temperature: every 5°F above 70°F lowers the correction by 10%, and every 5°F below raises it, capped at ±30%. The demand then rounds to the nearest standard halogen step of 40, 90, or 100 W.

Halogen heat depends on distance, mesh, and fixture, so the number is a starting point only. Run every heat source on a thermostat, place the probe on the animal’s activity surface, and use a CHE, DHP, or thermostat-controlled heat mat for night and ambient top-up.

## Heat lamp FAQ

**Q: What wattage heat lamp does a bearded dragon need?**

ReptiFiles recommends starting with a cluster of 2× 90–100 W halogen floods in a 24-inch-high enclosure. With the 48×24 in footprint, 24 in height, and a 70°F room, this calculator returns 100 W per bulb. Check that the basking surface stays near the 108–113°F target from ReptiFiles’ bearded dragon temperatures guide, using a thermostat probe.

**Q: What wattage heat lamp does a ball python need?**

ReptiFiles’ ball python care guide suggests about 2× 90 W halogen floods in a 4×2×2 ft enclosure. At 18 in height and a 70°F room, this calculator returns 90 W. Confirm the warm-side temperature with a thermostat probe before you rely on the wattage.

**Q: How does enclosure height change the recommended wattage?**

The estimate scales linearly with enclosure volume, so height matters as much as footprint. For a bearded dragon with the 48×24 in footprint, dropping from the 24 in reference height to 18 in lowers the demand to 75 W and rounds to the 90 W step. A 36 in tall enclosure raises the demand to 150 W and caps at the 100 W step, which points back to the two-bulb cluster in the care guide.

**Q: How much does room temperature affect heat lamp wattage?**

Room temperature adjusts the estimate by 2% per degree away from 70°F, capped at ±30%. In an 85°F room, a ball python at 18 in height drops from 90 W to the 40 W step, because the room already carries much of the heat load. At 55°F the same setup demands 117 W and stays at 100 W, so add a CHE or DHP for night and ambient top-up, as ReptiFiles advises.

**Q: Do crested geckos need a heat lamp?**

Crested geckos need warmth but not intense basking. ReptiFiles recommends keeping the vivarium around 72–78°F and starting heat at about 40 W. At 24 in height and a 70°F room, this calculator returns 40 W, so a low-wattage halogen or incandescent on a thermostat covers the warm side.

## Related care calculators

- [Reptile UVB Calculator](/reptile/uvb-calculator/) — Bulb distance and UV index by species, the lighting half of the same setup.
- [Pet Snake Care for Beginners](/reptile/snake-care/) — Ball python and corn snake enclosure, temperature, and humidity guidance.
- [All Reptile Care Tools](/reptile/) — The reptile hub, including UVB, humidity, temperature, and feeding tools.

## References

All starting wattages and temperature targets come from the ReptiFiles species care guides below, accessed September 2026.

- [Thermoregulation and aggregation in neonatal bearded dragons (Pogona vitticeps)](https://doi.org/10.1016/j.physbeh.2010.02.019) — Khan JJ, Richardson JM, Tattersall GJ, Physiol Behav, 2010.
- [ReptiFiles — Bearded Dragon Care Guide](https://reptifiles.com/bearded-dragon-care/) — ReptiFiles. Source of the 2× 90–100 W halogen starting point and enclosure guidance for bearded dragons.
- [ReptiFiles — Bearded Dragon Temperatures & UVB](https://reptifiles.com/bearded-dragon-care/bearded-dragon-temperatures-uvb/) — ReptiFiles. Source of the 108–113°F basking surface target and the verify-with-a-thermostat guidance.
- [ReptiFiles — Ball Python Care Guide](https://reptifiles.com/ball-python-care-guide/) — ReptiFiles. Source of the 2× 90 W halogen starting point for a 4×2×2 ft ball python enclosure.
- [ReptiFiles — Crested Gecko Care Guide](https://reptifiles.com/crested-gecko-care/) — ReptiFiles. Source of the 40 W heat starting point and the 72–78°F enclosure target for crested geckos.

_Educational resource, not veterinary advice. PetGuideCalc — https://petguidecalc.com_