About Sleep Time Calculator
Free sleep time calculator based on 90-minute sleep cycles. Find your ideal bedtime, best wake-up time, or perfect nap length in seconds — no sign-up.
Sleep Time Calculator is a free sleep time calculator based on 90-minute sleep cycles. Enter when you want to wake up (or go to bed) and get ideal bedtimes, wake-up times, or nap lengths in seconds. It explains how cycles move through light, deep, and REM sleep, why about 14 minutes of falling-asleep time is added, and what the tool is not. No account required.
