Interactive calculator
Sleep Cycle
Calculator
Sleep runs in roughly 90-minute cycles. Waking at the end of one — rather than mid-cycle — tends to feel less groggy. Work backward from your alarm, or forward from now.
Plan around
min
Best bedtimes
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This calculator is for educational purposes only and is not medical advice, diagnosis, or treatment. Results are estimates based on published formulas and population averages — your individual values may differ. Nothing here is calculated on a server: everything runs in your browser and no data is stored or sent anywhere. Always consult a qualified clinician before making health, medication, or training decisions.