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Bearded dragons regulate their body temperature by moving between hot and cool areas, and they rely on UVB to make vitamin D3 and absorb calcium. Enter your readings below — use a temperature gun on the basking surface, since air probes read far lower than the rock your dragon lies on.
Temperature chart
| Zone | Babies & juveniles | Adults |
|---|---|---|
| Basking surface | 105–110 °F (40–43 °C) | 95–105 °F (35–40 °C) |
| Warm side air | 85–95 °F (29–35 °C) | 85–95 °F (29–35 °C) |
| Cool side | 75–85 °F (24–29 °C) | 75–85 °F (24–29 °C) |
| Night | 65–75 °F (18–24 °C) | 65–75 °F (18–24 °C) |
| Humidity | 30–40% | 30–40% |
Lights on 12–14 hours in summer, around 10–12 in winter. At night all lights go off; if the room drops below about 65 °F (18 °C), use a ceramic heat emitter on a thermostat — never a colored “night bulb”.
UVB: bulb types and distances
| Bulb | Typical distance to basking spot (no mesh) | Notes |
|---|---|---|
| T5 HO 12% (e.g. Arcadia Desert 12%) | 12–18 in (30–45 cm) | Most popular choice for adults |
| T5 HO 10% (e.g. ReptiSun 10.0 T5 HO) | 10–16 in (25–40 cm) | |
| T5 HO 6% / 5.0 | 6–12 in (15–30 cm) | For shorter enclosures |
| T8 10% | 6–10 in (15–25 cm) | Weak; T5 HO preferred |
| Compact / coil | — | Not recommended |
The goal is a UV index of about 3–6 at the basking spot (Ferguson zone 3–4, as used by reptile lighting researchers). A mesh screen blocks roughly 30–50% of UVB, so mount the tube closer or inside the enclosure. The only way to be sure is to measure with a UV index meter such as the Solarmeter 6.5. Replace T5 tubes about every 12 months even if they still light up.
Enclosure size
| Dragon | Minimum enclosure |
|---|---|
| Adult | 4 × 2 × 2 ft (120 × 60 × 60 cm), about 120 gallons |
| Juvenile | Can start in the adult enclosure with plenty of cover |
FAQ
Why does my dragon sit with its mouth open?
Gaping while basking is normal thermoregulation. Gaping all day on the cool side, or with bubbles or mucus, can mean it’s too hot or a respiratory infection — check temperatures and see a vet if it persists.
Are heat rocks safe?
No. Heat rocks and under-tank heaters cause belly burns because dragons sense heat from above. Use an overhead basking bulb.
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