Sleep Cycle Calculator
Calculate your ideal bedtime or wake-up time based on natural sleep cycles
Click the input above to set a time
Sleep cycle length varies by individual (typically 70–120 minutes). These are general estimates based on 90-minute average cycles, not a substitute for professional sleep guidance.
How Sleep Cycles Work
During a typical night, your body goes through multiple sleep cycles, each lasting approximately 90 minutes. Each cycle consists of light sleep, deep sleep, and REM (rapid eye movement) sleep. Waking up at the end of a cycle — rather than in the middle of deep sleep — helps you feel more rested and alert.
How to Use This Calculator
Choose between two modes: "What time should I wake up?" if you know your bedtime, or "What time should I go to bed?" if you have a target wake-up time. Enter your time and the calculator shows 4 to 7 cycle options, each with the total sleep duration. The calculator factors in an average 15-minute window to fall asleep.
Why 90 Minutes?
Research suggests that a full sleep cycle averages around 90 minutes for most adults. While individual variation exists (typically 70–120 minutes), the 90-minute average provides a practical baseline for planning your sleep schedule. Aiming to complete full cycles rather than waking up mid-cycle can significantly improve how you feel in the morning.