Wellness estimates

Sleep Calculator

Calculate the best bedtime or wake-up time to complete full 90-minute sleep cycles and wake feeling rested. Use this Health estimates tool to enter your numbers, review the result, and understand the key assumptions before making the next decision.

What you get
A focused calculator, clear explanation, common questions, and useful next tools.
Quick intro
Calculator
Result
Explanation
Common questions
Related tools

Calculator tool

How this calculator works
The result depends on the numbers you enter and the assumptions shown below.

Sleep occurs in 90-minute cycles. Waking at the end of a cycle — rather than mid-cycle — helps you feel more refreshed. This calculator suggests times aligned to complete cycles plus ~14 minutes to fall asleep.

Review the inputs carefully and treat the output as an estimate. For decisions involving money, taxes, health, law, or security, compare the result with trusted professional guidance when needed.

Frequently asked questions

How many sleep cycles do I need?

Most adults need 5–6 complete cycles (7.5–9 hours). Each cycle is approximately 90 minutes, progressing through light, deep, and REM sleep.