An adult White's tree frog is a large, heavy-bodied climber, so its home needs height and strength more than it needs a long floor. For one adult, plan on a vivarium at least 18 by 18 by 24 inches tall. For a pair, or for a particularly large single frog, step up to roughly 24 by 18 by 36 inches so each animal can choose a separate sleeping perch and move away from the other at night when both become active.
Why vertical space matters for this frog
In the wild these frogs spend the day tucked on branches and leaves above the ground and wake at dusk to hunt and soak. A tall enclosure lets you recreate that vertical day-to-night movement: high, sheltered spots for sleeping, mid-level branches for the evening climb down, and a ground-level water dish deep enough for a proper soak. A short, wide tank wastes most of what this species actually uses, and a frog that cannot climb up to a quiet perch will often wedge itself behind fittings or press against the lid instead.
Furnishing the space so it is usable
Not all of that volume counts. Bare glass walls give a White's tree frog almost nowhere to go, so fill the height with thick branches, cork rounds, and sturdy artificial or live plants with broad leaves that can support a chunky adult without bending to the floor. Place at least two sleeping options at different heights, add a visual barrier of foliage on one side so the frog feels hidden during the day, and keep the water dish on the floor where it is easy to clean daily. Avoid thin twiggy decor sold for tiny froglets — an adult will snap or dislodge it on the first climb.
Floor, humidity, and the space around the tank
Floor area still has a job: it holds the water dish, catches waste where you can spot it, and gives a hunting frog room to lunge at food without hitting glass. Keep substrate simple and easy to replace in the feeding zone. The vivarium itself needs a spot away from direct sun and household heat sources, because a tall glass tank in a bright window can warm quickly, and this species prefers a warm but not hot daytime range with a gentle drop at night. Leave working room above the lid for misting and light fittings, and enough clearance in front of the doors that a startled frog cannot leap straight onto the floor during cleaning.
When to size up
Juveniles can start smaller, but they grow fast in their first year, and repeatedly rehoming a shy frog is more stressful than buying the adult size once. If your frog regularly sleeps on the floor, cannot find a perch wide enough to sit with all four feet supported, or if two frogs keep choosing the same single spot and displacing each other, the enclosure is telling you it is too small or too sparsely furnished. Measure the frog's chosen perches, not just the tank, when you judge the fit.
Keeping the final dimensions, perch layout, and misting routine in one place stops a well-meaning helper from moving a branch the frog relies on, and KinsLe's Family Sharing keeps that layout visible to everyone who cares for the frog.