Sleep Calculator
NEWFind a bedtime or wake-up time that lines up with your sleep cycles.
How to use Sleep Calculator
Based on 90-minute sleep cycles, plus 14 minutes to fall asleep.
- Choose whether you want to set a wake-up time or a bedtime.
- Enter that time.
- See a list of matching times, each a whole number of 90-minute sleep cycles apart.
Frequently asked questions
Why does it suggest specific times instead of just '8 hours'?
Sleep happens in roughly 90-minute cycles, and waking up mid-cycle tends to leave you feeling groggier than waking up at a cycle boundary. The tool works backward or forward in whole 90-minute cycles from your target time so you wake up between cycles instead of mid-cycle.
What does the extra 14 minutes account for?
The average time it takes a person to fall asleep after getting into bed — it's added to each cycle calculation so the suggested bedtime accounts for you not falling asleep instantly.
Why are there only two time options shown?
It shows 5 cycles (~7.5 hours) and 6 cycles (~9 hours) of sleep, covering the typical recommended range for adults — you can still calculate other cycle counts manually using the same 90-minute-cycle logic.
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