Sleep Calculator
Plan 7, 8, or 9 hours of sleep from a bedtime or wake time.
Calculate your estimate
What this tool tells you
Use this planner to see possible sleep windows based on the 7–9 hours per night commonly recommended for adults. It does not predict sleep stages or guarantee that you will feel rested.
How the estimate works
The calculator adds or subtracts exactly 7, 8, or 9 hours from your chosen clock time. These are simple schedule windows based on adult sleep-duration guidance, not a sleep-cycle formula. Allow additional time to fall asleep if you need it.
Important limitations
Sleep quality, sleep latency, shift work, age, and health conditions affect individual needs. If you have persistent insomnia, daytime sleepiness, or breathing symptoms during sleep, seek clinical advice.
Frequently asked questions
Why are there three times?
Adults are commonly advised to aim for 7–9 hours. The options show several planning windows within that range.
Does this account for time to fall asleep?
No. The results are time asleep. Add your usual wind-down and sleep-onset time when planning bedtime.
Does waking at a particular cycle make sleep better?
Sleep cycles vary. This tool avoids promising a cycle-perfect wake time and focuses on adequate sleep opportunity.