Sleep Calculator
Find the best bedtime or wake-up time based on 90-minute sleep cycles.
Best wake-up time (5 cycles)
6:14 AM
7h 30min · 5 sleep cycles
N1N2N3REM
Includes ~14 min to fall asleep · Each cycle ≈ 90 min
All Options
3:14 AM
Fair
3 cycles · 4h 30m
4.5 hours – short-term only
4:44 AM
Good
4 cycles · 6h
6 hours – minimum for most
6:14 AM
Ideal
5 cycles · 7h 30m
7.5 hours – recommended for adults
7:44 AM
Excellent
6 cycles · 9h
9 hours – fully restorative
Sleep Cycle Stages
N1
Light Sleep
5–10 min/cycle
Transition to sleep, easily woken
N2
Sleep Onset
20–30 min/cycle
Body temperature drops, heart slows
N3
Deep Sleep
20–30 min/cycle
Most restorative. Hard to wake.
REM
REM Sleep
20–25 min/cycle
Dreaming. Memory consolidation.
Find the best times to wake up or go to bed based on 90-minute sleep cycles. The calculator shows options for 3–6 complete cycles including the ~14 minutes it takes to fall asleep, with sleep quality ratings and a visual clock.
Key Features
Bedtime and wake-up modes
Enter either your bedtime or wake-up time. The tool calculates the optimal corresponding time for 3, 4, 5, and 6 sleep cycles.
SVG analogue clock visual
An interactive clock face shows a coloured arc from your sleep time to wake-up time, making your sleep window immediately visible.
Sleep quality ratings
Each cycle option is rated as Excellent, Ideal, Good, or Fair with a brief explanation of what that sleep duration means for recovery.
Sleep stage breakdown
A colour-coded cycle timeline bar shows N1, N2, N3 (deep sleep), and REM stages. A reference card explains each stage.
How to Use
- 1Choose whether you know your bedtime or your desired wake-up time.
- 2Enter the time using the time picker.
- 3View the four wake-up or bedtime options (3–6 cycles).
- 4The 5-cycle option (7.5 hours) is highlighted as the ideal recommendation.