Sleep Calculator
Enter your desired wake-up time to find the best bedtimes — or enter when you're going to sleep to find ideal wake-up times. Results are based on 90-minute sleep cycles plus the average 14 minutes it takes to fall asleep.
To wake up at 7:00 AM, go to sleep at:
Advertisement
Frequently Asked Questions
How does a sleep calculator work?
Sleep happens in repeating 90-minute cycles, each moving through light sleep, deep sleep, and REM. Waking up at the end of a complete cycle — rather than in the middle of deep sleep — is what makes the difference between feeling rested and feeling groggy. This calculator works backward from your wake time (or forward from your bedtime) to find times that land at the end of a full cycle.
Why does the calculator add 14 minutes?
On average it takes about 14 minutes to fall asleep after getting into bed. The calculator adds this sleep onset time so that the cycles are counted from when you actually drift off, not from when you lie down.
Does sleep need differ by gender or age?
Yes — meaningfully so. The National Sleep Foundation recommends women target 7–9 hours while men do well at 7–8 hours (5 cycles, or 7.5 hours, is the sweet spot for men). Teenagers need more: the NSF recommends 8–10 hours for ages 14–17, meaning 4 cycles (6 hours) is insufficient for teens, not merely "acceptable." Adults 65 and older align with the male range — 7–8 hours. Select your profile above and the calculator will adjust the labels accordingly.
What if none of the recommended times work for my schedule?
Aim for the highest cycle count that fits your constraints. 4 cycles (6 hours) is better than an unfinished 5th cycle that cuts off in the middle of deep sleep. If your schedule forces short sleep regularly, try shifting your bedtime earlier in 90-minute increments rather than sleeping in later, which can disrupt your circadian rhythm.