Calculate possible bedtimes and wake-up times with clear assumptions.
These times are calculation examples. Getting enough sleep matters more than matching the end of an assumed 90-minute cycle.
Start with when you need to wake up and allow enough time for sleep. The general recommendation for adults is 7–9 hours. Sleep cycles vary; a calculator cannot identify your exact sleep stage.
Times are counted back from your alarm or forward from now. The model uses 90 minutes per calculation cycle and 15 minutes to fall asleep. These fixed assumptions describe the arithmetic, not your personal biology.
No. Sleep cycles vary. This tool does not measure sleep, REM stages or when you will feel rested.
Use it to help reserve time. Choose a sleep duration that meets your needs and allow for falling asleep to take more or less than the assumed 15 minutes.