Sleep Cycle Calculator
See how many full 90 minute sleep cycles fit into the sleep you get, and what the leftover minutes mean for your morning.
How long you expect to sleep, in minutes.
90 minutes is the commonly used average.
Your cycle breakdown will appear here after you calculate.
How it works
A sleep cycle moves through light sleep, deep sleep, and dreaming before starting again, taking about 90 minutes on average. This calculator divides your total sleep by the cycle length to show how many complete cycles fit and how much time is left over.
The leftover minutes are not wasted, but a large remainder means your alarm may land mid-cycle. Shifting bedtime or the alarm by roughly that amount can line the end of your sleep up with the end of a cycle. Remember that 90 minutes is an average; real cycles range about 80 to 120 minutes.
These calculators give planning estimates based on average sleep cycle timing. They are not medical advice and cannot diagnose sleep problems. If poor sleep persists, talk to a clinician.