# Reptile egg incubation temperature & sex determination

> Select a species and enter an incubation temperature to compare it against the attested 82–90 °F (28–32 °C) band for bearded dragon eggs. TSD (temperature-dependent sex determination) is the evidence framework behind the check: other species are marked source pending, and every result is framed as evidence and risk, not certainty.

## Interactive calculator

Use the interactive calculator on the page: https://petguidecalc.com/reptile/incubation-temperature/ — select a species and enter an incubation temperature to get a band judgment with probability-framed risk.

## What is the right reptile egg incubation temperature?

For bearded dragon eggs, the attested incubation band is 82–90 °F (28–32 °C), from Holleley et al. (2015). Below it, hatching success drops; at 97 °F (36 °C) and above, that study documented genetic males hatching as female-phenotype animals. Leopard geckos, crested geckos, ball pythons, and corn snakes have no published data in our reference set yet, so their status is source pending.

## Species incubation evidence at a glance

| Species | Attested data | Range | Sex-reversal line | Notes |
|---|---|---|---|---|
| Bearded dragon | Yes | 82–90 °F (28–32 °C) | ≥ 97 °F (≥ 36 °C) | Attested incubation band of 28–32°C, with sex reversal of genetic males (ZZ → ZZf) documented at 36°C and above in Holleley et al. (2015). |
| Leopard gecko | Source pending | None | None | Source pending — no published incubation data for this species in our reference set yet. |
| Crested gecko | Source pending | None | None | Source pending — no published incubation data for this species in our reference set yet. |
| Ball python | Source pending | None | None | Source pending — no published incubation data for this species in our reference set yet. |
| Corn snake | Source pending | None | None | Source pending — no published incubation data for this species in our reference set yet. |

## Bearded dragon incubation bands

| Reading | Implication | Source |
|---|---|---|
| < 82 °F (< 28 °C) | Below the attested 28–32°C band. Expect longer incubation and lower hatching success; there is no sex-reversal evidence at these temperatures. | Holleley et al. 2015 |
| 82–90 °F (28–32 °C) | Inside the attested band used in Holleley et al. (2015). Hatching success is highest here, and offspring sex follows the usual genetic pattern. | Holleley et al. 2015 |
| 90–97 °F (32–36 °C) | Above the attested band. Higher temperatures reduce hatching success, and incubation in the female-producing range becomes more likely. This is a risk statement, not a prediction. | Holleley et al. 2015 |
| ≥ 97 °F (≥ 36 °C) | At 36°C and above, Holleley et al. (2015) documented sex reversal of genetic males (ZZ) into female phenotype (ZZf) in the study population. The likelihood rises with temperature and duration — treat this as a risk warning, not a guarantee. | Holleley et al. 2015 |

## How the incubation check works

Only one species in this tool has attested incubation data: the bearded dragon. Holleley et al. (2015) incubated eggs across a temperature series and reported a working band of 82–90 °F (28–32 °C), with hatching success highest inside it. The same study documented sex reversal at 97 °F (36 °C) and above.

Every other species here is marked source pending. Incubation figures for leopard geckos, crested geckos, ball pythons, and corn snakes circulate among keepers, but no published band matched our reference set, so the tool does not guess.

The output is a band judgment with probability-framed risk. Nothing on this page predicts the sex of any individual hatchling; the evidence describes what happened in a study population.

Worked example: run 98 °F (36.5 °C) through this checker for a bearded dragon and it returns ABOVE RANGE. The result panel attaches the study note: At 36°C and above, Holleley et al. (2015) documented sex reversal of genetic males (ZZ) into female phenotype (ZZf) in the study population. The likelihood rises with temperature and duration — treat this as a risk warning, not a guarantee.

## Incubation questions

**Q: What temperature should I incubate bearded dragon eggs at?**

Holleley et al. (2015) used a working band of 82–90 °F (28–32 °C), and hatching success is highest inside it. Keep the incubator stable in that range and measure the egg temperature rather than relying on the air reading. ReptiFiles’ bearded dragon guide covers incubation and hatchling setup in more detail.

**Q: At what temperature does bearded dragon sex reversal happen?**

In Holleley et al. (2015), sex reversal of genetic males (ZZ) into female-phenotype animals (ZZf) was documented at 97 °F (36 °C) and above in the study population. The likelihood rises with temperature and exposure time. It is a documented outcome in that population, not a guarantee for any clutch.

**Q: Is incubation temperature the same for every reptile species?**

No. Leopard geckos, crested geckos, ball pythons, and corn snakes are marked source pending here because no published band matched our reference set. Use a species-specific breeding guide for those animals instead of the bearded dragon numbers.

**Q: Does incubation temperature guarantee hatchling sex?**

No. Temperature-dependent sex determination is a population-level pattern, and Holleley et al. (2015) reported it as evidence within their study population. Individual clutches vary with genetics, egg quality, and incubation conditions, so treat any temperature guide as risk information, not a prediction.

**Q: What happens if I incubate below 82 °F (28 °C)?**

Below the attested 82–90 °F (28–32 °C) band, hatching success drops and incubation runs longer. Holleley et al. (2015) reported no sex-reversal evidence at those temperatures. Humidity and egg quality still affect outcomes, so follow a breeding guide and check eggs regularly.

## References

The incubation band and the sex-reversal line come from a peer-reviewed study; the care guide provides breeding and husbandry context.

- [Developmental dynamics of sex reprogramming by high incubation temperatures in a dragon lizard](https://doi.org/10.1186/s12864-022-08544-2) — Whiteley SL, Holleley CE, Georges A, BMC Genomics, 2022.
- [Sex reversal triggers the rapid transition from genetic to temperature-dependent sex](https://doi.org/10.1038/nature14574) — Holleley CE, O’Meally D, Sarre SD, Graves JAM, Ezaz T, Matsubara K, Azad B, Zhang X, Georges A, Nature, 523(7559), 79–82, 2015. Documents the attested 82–90 °F (28–32 °C) incubation band and sex reversal of genetic males (ZZ → ZZf) at 97 °F (36 °C) and above in the study population of Pogona vitticeps.
- [Bearded Dragon Care Guide (ReptiFiles)](https://reptifiles.com/bearded-dragon-care/) — ReptiFiles, Online care guide. Breeding and husbandry context for bearded dragons, including incubation and hatchling care.

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