Sleep Calculator
About the Sleep Cycle Calculator
This sleep calculator helps you decide when to wake up or when to go to bed so you finish full 90-minute sleep cycles. Waking up in the middle of a deep cycle is what makes you feel groggy — finishing a cycle leaves you noticeably more rested even after the same total hours of sleep.
Sleep Cycle Calculator
A typical adult sleep cycle lasts about 90 minutes and moves through light sleep, deep sleep, and REM sleep before repeating. This sleep cycle calculator shows 4 to 6 cycle options ranging from 4.5 hours to 9 hours — the 5- and 6-cycle options (7.5 h and 9 h) are highlighted as the recommended targets for most adults. Use it as a rem sleep calculator to align your wake time with the end of a REM phase rather than the middle of one.
Bedtime Calculator: What Time Should I Go to Bed?
If you have a fixed alarm in the morning, the bedtime calculator mode answers "what time should I go to bed?" — pick your wake-up time and you'll get the bedtime options that finish on a full cycle. Each option already includes a 14-minute buffer for falling asleep, which you can edit if you typically take longer or shorter to drift off.
Wake Up Calculator: What Time Should I Wake Up?
Going to bed at a fixed time? The wake up calculator mode answers "what time should I wake up?" — pick your bedtime and the tool lists wake-up options that land at the end of a cycle. This is also useful as a quick sleep estimator when planning naps or short overnight rests.
How to Use This Sleep Pattern Calculator
Pick the mode that matches what you know — your wake-up time or your bedtime. The calculator returns the matching times for 3, 4, 5, and 6 cycles. The recommended 7.5-hour and 9-hour options are highlighted because they're the most commonly cited adult sleep targets. Adjust the fall-asleep buffer if you tend to drop off faster or slower than average.
Related Tools
Once your sleep schedule is set, plan the rest of your day with the Pomodoro Timer for focused work sessions or the Work Hours Calculator to track time and pay. Align your wake time with daylight using the Sunrise & Sunset Calculator, and for quick alarms or interval timing try the Online Timer or Countdown Timer.