Sleep Calculator Online
Choose a direction, enter a time, and compare a custom duration with 3–6 cycle plans.
A QUICK WALKTHROUGH
How to use this tool
- Choose bedtime-to-wake or wake-to-bed planning.
- Enter your custom duration or cycle assumptions.
- Review the time results and relative day labels.
Planning calculation
This local clock calculation uses only the values you enter. Cycle length and fall-asleep time are assumptions for planning, not medical guidance.
GOOD TO KNOW
Common questions
Can I plan from bedtime instead?
Yes. Switch the direction to calculate wake-up times.
Can I change the cycle and latency assumptions?
Yes. The defaults are 90 minutes per cycle and 14 minutes to fall asleep, and both are adjustable.