Bedtime Calculator

Work backwards from your wake time. Sleep runs in roughly 90-minute cycles, and waking at the end of one feels considerably better than waking in the middle.

Sleep is not a flat block. It runs in cycles of roughly 90 minutes, each moving from light sleep through deep sleep and into REM. Waking at the end of a cycle feels considerably better than being pulled out of the middle of one, which is why two people who slept the same number of hours can feel completely different.

This works backwards from the time you have to be up.

Fill in the fields above and the answer updates as you type. Nothing is stored or sent anywhere.