Sleep Calculator
Wake up refreshed by timing your sleep around complete 90-minute cycles. Enter when you need to wake — or when you're going to bed now.
Show solution steps
What is the Sleep Calculator?
A sleep calculator uses the roughly 90-minute sleep cycle to suggest bedtimes or wake times. Waking at the end of a cycle, rather than mid-cycle, helps you feel more rested.
How to Calculate
Working back (or forward) in 90-minute cycles from your target time, plus about 15 minutes to fall asleep, gives several good options.
Formula
Each cycle ≈ 90 minutes; aim for 5–6 complete cycles.
How to Use
- Enter your details in the fields above.
- The result updates instantly as you type.
- Use Copy, Print or Download PDF to save your result.
Frequently Asked Questions
How many sleep cycles do I need?
Most adults do well with 5u20136 cycles (about 7.5u20139 hours). Waking at the end of a cycle usually feels better than waking in the middle of one.
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