Free Sleep Cycle & Optimal Wake Time Calculator Online
Calculate the ideal time to fall asleep or wake up based on 90-minute ultradian sleep cycles to eliminate grogginess and sleep inertia. — 100% free online utility, zero sign-up, zero paywalls, and private client-side processing.
How It Works
Choose Mode
Select 'I want to wake up at...' or 'If I go to bed now...'.
Factor In Fall-Asleep Latency
Standard default adds 14 minutes average time to fall asleep.
Calculate 90-Minute Cycles
Evaluates 4, 5, or 6 complete sleep cycles (6h, 7.5h, or 9h total sleep).
Pick Target Alarm
Set your alarm to wake at the conclusion of a sleep cycle.
Frequently Asked Questions
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