Reptile Age & Growth Estimator

Last updated: · Reviewed against sources listed below

How old is my bearded dragon? This reptile age calculator estimates age from length or weight for bearded dragons, leopard geckos and ball pythons. Add a known age to see whether your pet is within the normal range, underweight or overweight.

Measure by

Weigh on a kitchen scale before feeding.

What the result means: the estimated age is the span of ages at which healthy captive animals typically have the size you entered. It is widest for adults, because growth slows and stops. Treat it as a rough guide, not proof of age.

How it works

For each species we store a growth table of typical length and weight ranges at set ages, such as hatchling, 3 months and 6 months. Between those ages the tool fills in the gaps with straight-line interpolation, so it has a normal range for every month.

Estimating age: the tool checks every month from hatching to adulthood and lists the months whose normal range contains your measurement. The first and last matching months give the estimated age span. If your number is above the adult range, the result is “adult”; if it is below the hatchling range, the tool asks you to double-check.

Checking condition: if you enter a known age, the tool looks up the normal range for that age and tells you whether your measurement is below, within or above it. Only weight is used to flag “light” or “heavy,” because length says little about body condition.

Reference data

The full growth tables are on each species’ growth chart page:

Frequently asked questions

How old is my bearded dragon?

Weigh or measure your dragon and enter it above. Up to about 12 months, size gives a useful estimate, because dragons grow fast and fairly predictably. After that, adults of very different ages look alike, so the tool can only say “adult.” A vet can sometimes narrow it down using bone density and other signs.

Is weight or length better for estimating age?

Length is usually better for estimating age because it is less affected by recent meals. Weight is better for checking condition, because it changes quickly when an animal is underfed or overfed. If you can, measure both: estimate age from length, then enter that age and the weight to check condition.

Why is my reptile smaller than the chart for its age?

Common reasons are low temperatures, weak or old UVB, too little food when young, parasites and stress from shared housing. Genetics matters too: some animals are simply small. If your pet is below the range and also losing weight or looking thin, see a reptile vet.

Can a reptile be too big for its age?

Yes. Fast growth is often a sign of overfeeding, especially in snakes fed very often and lizards given many fatty worms. Rapid growth can come with obesity and health problems. Check body shape as well as numbers, and follow the feeding schedule for your animal’s age.

Sources

Where sources disagree we show the range they share. See our sources and methodology for how every number is checked.

Results are estimates for healthy animals. Always consult a reptile veterinarian for individual advice. Read our disclaimer.

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