Using the Sleep Calculator
Enter the amount of sleep you want, then add a separate allowance for falling asleep. The tool subtracts both from the wake time and wraps around midnight. For a 07:00 wake time, eight hours of sleep and fifteen minutes to fall asleep give a bedtime of 22:45.
Worked example
Use the example inputs below to reproduce this result. These are the form's starting values, not recommended targets. Changing your inputs updates your result above; this worked example stays fixed for comparison. Results are rounded for display.
Example inputs
- Wake-up time
- 07:00
- Desired sleep (hours)
- 8
- Time to fall asleep (minutes)
- 15
Example result
- Go to bed at
- 22:45
Method and assumptions
Subtracts sleep duration and sleep-onset time from wake-up time. Sleep cycles are variable; this tool does not assume fixed 90-minute cycles.
Allow time for the whole bedtime routine
The calculation reserves time for sleep and the entered delay before falling asleep. It does not schedule the activities that happen before getting into bed. If you need time for a routine, place that earlier in your schedule. Keep planned sleep duration separate from time merely spent in bed when comparing records.
Common question
Does the result guarantee I will wake at the end of a sleep cycle?
No. The tool does not predict sleep stages or use fixed ninety-minute cycles. It only subtracts durations from a wake time. Actual sleep timing and quality cannot be determined from these three entries.
Guide updated .