Two to three inches, legs included in the impression
A red-eyed tree frog finishes growing at roughly 2 to 3 inches from nose to vent. Males settle at the smaller end, commonly 2 to 2.5 inches, while females grow noticeably larger and heavier, sometimes reaching about 3 inches. The body itself stays slim, so the frog looks bigger than it is: those very long hind legs, wide toe pads, and bulging red eyes give a mature frog a presence that its modest length does not suggest. A resting adult folded on a leaf, legs tucked tight, can look half its stretched size.
Why females outgrow males
The size gap between the sexes is normal and useful in the wild, where a larger female can carry more eggs and a smaller male can ride on her back during breeding without weighing her down. In a home terrarium, the difference helps you sex adults at a glance, alongside the male's darker throat patch used for calling. When buying, remember that a group of juveniles will not stay uniform: the females will pull ahead in both length and girth, and the enclosure and feeding plan should be built around the largest frog you will eventually house.
Housing built for a leggy adult
Length alone understates what this frog needs. A 3-inch red-eyed tree frog spends its nights climbing, leaping between leaves, and plastering itself to glass, so a tall enclosure with broad-leaved plants, smooth branches, and vertical space suits the adult far better than a low, wide box. Leaves must hold a sleeping frog's weight all day without folding, and the lid needs a secure fit because a slender frog squeezes through surprisingly narrow gaps. Give each adult room to choose its own sleeping leaf, since tankmates that crowd one favorite perch can stress the smaller males. A water bowl wide enough for a full-body soak completes the adult's nightly circuit between leaves, glass, and feeding perches.
Feeding and watching growth
Adults take medium crickets and similar insects, offered at night when the frogs wake and begin hunting. A healthy grown frog looks smooth and well covered without bulging sides, and you can judge condition by the fullness above the hips rather than by length alone. Juveniles grow quickly on regular feeding and usually approach adult size within their first year or so. A frog that stops growing early, loses its rounded shape, or leaves food untouched night after night should prompt a review of temperature, humidity, and misting, and a vet conversation if the pattern continues.
Buying the adult you actually want
Because shop juveniles are tiny and nearly identical, confirm the sex mix and expected adult sizes before a group goes home with you, especially if you hope to hear males calling. Keep a simple growth note for each frog, with a photograph on the same leaf or beside the same object, so the change in size is easy to see across months. That record becomes part of the frog's story if its home ever changes, and KinsLe Transferrable Profiles sends the profile along to the new keeper with those growth notes and routines still attached.