Skip to content
2x2xKit

Sleep Calculator

Find the best bedtime based on 90-minute sleep cycles and your wake-up time.

How this is calculated
Bedtime = wake-up time − (sleep cycles × 90 minutes) − 14-minute fall-asleep buffer

Assumptions used in this calculation

  • Fall-asleep buffer: Assumes about 14 minutes to fall asleep, the average found in sleep-onset research.

About this calculator

The sleep calculator works backward from a target wake-up time in 90-minute sleep-cycle increments, showing several bedtime options so you can wake up between cycles rather than mid-cycle.

Worked example

Wake up at 7:00 AM

Result: Bedtime options: 9:46 PM, 11:16 PM, 12:46 AM, or 2:16 AM

Was this helpful?

Frequently asked questions

Related calculators

Heart Rate Zone Calculator

Find your training heart rate zones based on age and resting heart rate.