Sleep Calculator
Estimate suggested bedtime or wake-up times using 90-minute sleep cycles. Informational only, not medical advice.
This calculator uses a 90-minute cycle estimate and a 15-minute fall-asleep allowance when calculating bedtime suggestions.
Privacy: runs locally in your browser. No values are stored or transmitted.
How it works
This calculator uses a simple 90-minute sleep-cycle model. It suggests times based on 4, 5, or 6 cycles, which roughly correspond to about 6, 7.5, or 9 hours of sleep.
When calculating bedtime from a wake-up time, the tool also subtracts an extra 15 minutes as a simple fall-asleep allowance.
Examples
- Wake at 07:00 → suggested bedtimes around 20:45, 22:15, or 23:45
- Sleep at 23:00 → suggested wake times around 05:00, 06:30, or 08:00
- Useful for simple bedtime planning, not sleep diagnosis
FAQ
- What does this calculator do?
It estimates suggested bedtime or wake-up times using a typical 90-minute sleep cycle model.
- Are sleep cycles always 90 minutes?
No. Sleep cycles vary by person and by night, but 90 minutes is a common planning estimate.
- Does it include time to fall asleep?
Yes. This calculator adds a simple 15-minute fall-asleep allowance to bedtime planning.
- Is this medical advice?
No. It is an informational sleep-planning tool only.
- Are my times stored?
No. All calculations run locally in your browser and are not stored or transmitted.