How many sleep cycles do I need?

Most adults need 4–6 cycles per night (one cycle is about 90 minutes). Waking at the end of a cycle — rather than mid-cycle — is what makes you feel rested, and the calculator targets exactly that.

What time should I go to bed?

Work backward from your wake time in 90-minute cycles plus about 15 minutes to fall asleep. The calculator does this for any wake-up time and any number of cycles.

Wellness

Sleep Calculator

Optimal bedtime found

Find the best bedtime based on 90-minute sleep cycles. Wake up refreshed by aligning your sleep with natural sleep cycles.

Wake Time

I Want to Wake Up At

Based on 90-minute sleep cycles. Aim for 5-6 full cycles (7.5-9 hours).

Optimal Bedtimes

02:304.5h sleep

3 cycles

01:006h sleep

4 cycles

23:307.5h sleep

5 cyclesBest

22:009h sleep

6 cyclesBest

💡 Aim to fall asleep within 15 min of bedtime. Avoid screens 30 min before sleep.

If You Sleep Now

You'd get ≈ 19h 51m (≈13.2 cycles) until 07:00.

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How It Works

The Formula

Bedtime = WakeTime − 90min × n cycles

Sleep cycles average 90 minutes

Worked Example

Wake at 6:30 AM · 5 cycles

16:30 − 450 min
2Bedtime = 11:00 PM

Result: Go to bed at 11:00 PM

Pro Tip

Waking between cycles (not mid-cycle) leaves you far more refreshed.

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Frequently Asked Questions

How to Use This Calculator

Sleep Calculator: Wake Up Refreshed with the Perfect Bedtime

Learn how sleep cycles work and calculate your ideal bedtime. Wake up feeling refreshed with our free sleep calculator based on 90-minute cycles.

Read guide →

About the author

Calculatore.net Team

Our team of finance and math specialists builds every calculator with industry-standard formulas, then verifies each tool hands-on. Learn more in our blog & guides.