Sleep Cycle Calculator

Find the best times to go to bed or wake up by aligning your night to 90-minute sleep cycles, with the total sleep for each option and a timeline of your night.

What is fixed for you?

Quick presets

Fall-asleep time (how long it takes you to drift off)
Most adults need 10 to 20 minutes. This time is added on top of your sleep cycles.
Best time to go to bed
—
All cycle-aligned options
Go to bed at Sleep cycles Total sleep

One sleep cycle lasts about 90 minutes, and you feel most rested when you wake at the end of a cycle. For most adults 5 to 6 cycles (about 7.5 to 9 hours) is the recommended range.

Your night, cycle by cycle

Each block is one 90-minute cycle. The lighter strip at the start is the time it takes to fall asleep. Waking at a block edge, not in the middle, leaves you feeling more rested.

For beginners: how to read this
Why 90 minutesSleep moves through repeating cycles of light sleep, deep sleep and dream sleep. One full cycle averages about 90 minutes for most adults.
Aim for whole cyclesWaking at the end of a cycle feels easier than waking mid-cycle, even if the mid-cycle option gave you a few more minutes in bed.
Count the fall-asleep timeYou do not start a cycle the instant your head hits the pillow. The calculator adds your fall-asleep time before the first cycle begins.
5 to 6 cycles is the sweet spotThat is roughly 7.5 to 9 hours of sleep. Four cycles can work for a short night, three is a minimum, not a target.
These times are a general guide based on an average 90-minute cycle. Real cycle length varies from person to person and from night to night, and individual sleep needs differ. Use this as a starting point, not a medical recommendation.

To get a result, choose what is fixed for you. Pick «I want to wake up at» if your alarm is set and you need a bedtime, or «I’m going to bed at» if your bedtime is fixed and you want the best wake-up time. Then enter the time in 24-hour format and, if needed, adjust how long it takes you to fall asleep.

How the times are calculated

Sleep runs in repeating cycles of light sleep, deep sleep and dream sleep. One full cycle averages about 90 minutes, and you feel most rested when you wake at the end of a cycle rather than in the middle of one. The calculator works in whole 90-minute cycles and adds the time it takes you to fall asleep before the first cycle begins.

  • If you set a wake-up time: bedtime equals your wake-up time minus the number of cycles times 90 minutes, minus your fall-asleep time. It does this for 6, 5, 4 and 3 cycles.
  • If you set a bedtime: wake-up time equals your bedtime plus your fall-asleep time plus the number of cycles times 90 minutes, again for 6, 5, 4 and 3 cycles.

Each option is labelled with the number of cycles and the total sleep it gives, such as 6 cycles for 9h 00m or 5 cycles for 7h 30m. Times that cross midnight are handled correctly, so a late bedtime still maps to the right morning hour.

The recommended range

For most adults, 5 to 6 cycles — roughly 7.5 to 9 hours of sleep — is the sweet spot, and those rows are flagged as recommended. Four cycles (6 hours) can cover a short night, while three cycles (4.5 hours) is a minimum rather than a target. The timeline below the table shows the recommended option as a band of 90-minute blocks across the night, with the lighter strip at the start standing for the time it takes to drift off.

Fall-asleep time

You do not begin a sleep cycle the instant your head hits the pillow. Most adults take 10 to 20 minutes to fall asleep, so the calculator uses 15 minutes by default and lets you change it. A longer fall-asleep time pushes an earlier bedtime or a later wake-up time.

What is not included

This is a general guide built on an average 90-minute cycle. Real cycle length varies from person to person and from night to night, and individual sleep needs differ with age, health and recent rest. It does not account for sleep quality, naps, sleep disorders or medical conditions, and it is not a medical recommendation.