Things You'll Need
- 12-inch ruler
- Gram scale
Instructions
Remove your gecko from its tank and gently place it on a flat surface alongside a ruler or even on a ruler. Avoid picking it up by the tail, because the tail is fragile and easily broken off. If yours is a leopard gecko, which is the most popular lizard among U.S. herpetoculturists, and if it is an adult male, it may measure from 7 inches to 8 inches long from nose to tail. The adult female leopard may measure from 8 inches to 10 inches long. But remember, those measurements are approximate for full-size geckos and don't really tell you if you have a 6- or 8-year-old or a 1-year-old.
Weigh your gecko, using a gram scale. An adult male that has reached sexual maturity -- roughly 8 to 9 months of age -- should weigh at least 50 grams. An 8- or 9-month-old female should weigh at least 45 grams. Again, weights are approximate -- they could be higher or they could be lower -- and are in no way positive indicators of your pet's age.
Check out your gecko's colors or patterns. As a rule of thumb, younger geckos are more colorful than their more mature brethren; the babies are banded or have big blotches. As the gecko matures, the distinctive leopard-spot pattern emerges.