Calculator
Sleep duration calculator
Calculate an overnight sleep window and compare it with your duration target. Data is processed only in your browser, and the page explains the formula and limitations of the result.
Reviewed: 3 August 2026Processed locally
Calculator
Enter data
Bedtime, wake time and an individual duration target. Fields marked with an asterisk are required.
How to use the calculator
- Enter the required data: bedtime, wake time and an individual duration target.
- Check the values and select “Calculate”.
- Review the primary result and the detailed calculation components.
Calculation details
Formula and calculation method
Window duration = wake time − bedtime, accounting for crossing midnight.
Worked example
A window from 23:15 to 07:00 lasts 7 hours 45 minutes, exceeding a 7-hour target by 45 minutes.
Limitations
- This is time in the entered window, not measured sleep; it excludes sleep latency, awakenings and sleep quality.
Sources
Engine version: 1.0 · Last reviewed: 3 August 2026
Frequently asked questions
Is the entered data sent to a server?
No. The calculation runs locally in your browser and the values are not saved by default.
Is the result definitive?
Not always. This is time in the entered window, not measured sleep; it excludes sleep latency, awakenings and sleep quality.