Bedtime Calculator
Know when to go to bed based on the time you need to wake up
Click the input above to set a time
Sleep cycle length varies by individual (typically 70–120 minutes). These are general estimates based on 90-minute average cycles, not a substitute for professional sleep guidance.
What Time Should I Go to Bed to Wake Up at a Specific Time?
If you need to be up by a certain time — whether for work, school, or an early flight — this bedtime calculator works backward from your target wake-up time to suggest the best times to go to bed. It factors in both the average 90-minute sleep cycle and roughly 15 minutes to fall asleep, helping you plan for a full night of rest.
How the Bedtime Calculator Works
Enter the time you need to wake up. The calculator counts backward in 90-minute increments — each representing one full sleep cycle — and subtracts an additional 15 minutes for the time it typically takes to fall asleep. You'll see several candidate bedtimes, each corresponding to a different number of complete cycles (4 to 7 cycles, or 6 to 10.5 hours of sleep).
Which Bedtime Should I Choose?
For most adults, 5 to 6 full sleep cycles (7.5 to 9 hours) is a healthy target. The recommended option shown is 6 cycles, which gives you about 9 hours of rest. If you have limited time, 4 or 5 cycles may suffice, though consistently getting fewer than 5 cycles can lead to sleep deprivation over time. Choose the bedtime that best fits your schedule while giving you the most complete cycles.