Wake windows are simple - they’re the length of time your baby should be awake before sleeping again. Wake windows change as babies transition from 3 naps, to 2, to 1.
Every baby is different, and wake windows usually require a little experimentation! But generally speaking, here are the effective wake windows by age group:
Wake windows give a good indication of when it’s time to put your baby down for a nap (or bedtime)…but they’re also useful for telling you when NOT to put them down. If your baby is getting drowsy before their wake window is over, consider keeping them awake a little longer. Otherwise, they won’t be ready for bed early enough, and bedtime will slip later and later. That leads to overtiredness & crankiness that can persist from bedtime through the entire night.