Sleep Cycle Calculator — Best Times to Sleep or Wake

Wake between cycles, not mid-deep-sleep: enter your alarm — see six ideal bedtimes, fall-asleep buffer included.

Quick answer: Free sleep calculator: ideal bedtimes for your alarm in 90-minute cycles (3-6 cycles, 15-min fall-asleep buffer).

Mode Time

How to use

Choose wake-up or bedtime mode.
Enter the time.
Read the 3-6 cycle options.

General information only — not medical, financial or legal advice. Figures cross-checked against public official sources (IRS / HMRC / NHS / WHO guidance); content last reviewed September 2026. For decisions that matter, confirm with a licensed professional in your country.

About this tool

Waking mid-deep-sleep feels awful even after 8 hours; waking between cycles feels lighter. This tool works backwards from your alarm in 90-minute cycles (3-6 cycles), including the average 15-minute fall-asleep time — plus a wake-time mode.

FAQ

Is 90 minutes exact?

Population average — individuals range 80-120 min; adjust over a week.

Why 6 cycles?

Some adults need 9h — options listed so you can experiment.

15-minute buffer?

Average fall-asleep time — lie down at that minute.

Sleep-now mode?

Bedtime mode shows the alarms that complete cycles from now.

Naps?

One 90-min cycle, or 20 min before deep sleep starts.

Medical note?

Chronic insomnia needs a doctor — this is arithmetic, not medicine.

Rate this tool

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The complete sleep cycle calculator guide

Prefer the long version — a worked example, the mistakes people actually make, and answers to real questions? The blog guide Sleep Cycle Calculator — Complete Guide, Mistakes & FAQ covers all of it step by step.

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Sleep Cycle Calculator — Best Times to Sleep or Wake

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About this tool

FAQ

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The complete sleep cycle calculator guide