Sexual maturity for leopard geckos occurs at around a year of age, with males being bigger and broader than females. They also have a dark, prominent V-shaped row of pores in front of the cloaca, and an obvious bulge at the tail base. They may be more brightly colored than females, but this is not consistent.
Identifying the sex of a leopard gecko before maturity is extremely difficult, and it's usually worthwhile to just wait to find out, since probing by an amateur can harm the lizard.
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