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Sleep duration calculator

Sleep duration calculator: enter your values and get an instant free result.

Your result

Complete the fields and calculate.

Calculation method and formula

(Wake time − Time asleep) mod 24 h

Understand the inputs

Time asleep
Enter a time in 24-hour format.
Wake time
Enter a time in 24-hour format.

Assumptions and limitations

Times are handled within one day or across midnight. Without dates, multi-day intervals and daylight-saving changes cannot be identified. Count breaks or time to fall asleep only once.

The formula uses the specified units. Displayed numbers are rounded; whole packs, item counts and full time periods may also be rounded within the calculation.

Worked example

Illustrative values. Replace them with your own inputs for your calculation.

Time asleep
23:00
Wake time
07:00
Example result8 hr 0 min

The result was calculated directly from your entries.

Model revision: October 17, 2026 · How CleverCalc works

FAQ

Frequently asked questions

How does Sleep duration calculator work?+

(Wake time − Time asleep) mod 24 h. Times are handled within one day or across midnight. Without dates, multi-day intervals and daylight-saving changes cannot be identified. Count breaks or time to fall asleep only once.

What assumptions should I consider for this result?+

Times are handled within one day or across midnight. Without dates, multi-day intervals and daylight-saving changes cannot be identified. Count breaks or time to fall asleep only once. The formula uses the specified units. Displayed numbers are rounded; whole packs, item counts and full time periods may also be rounded within the calculation.

How accurate is the result?+

The formula uses the specified units. Displayed numbers are rounded; whole packs, item counts and full time periods may also be rounded within the calculation. Prices, measurements and model assumptions determine how well the result represents your situation.

Is this calculator free?+

Yes. Calculations and PDF export work without an account or registration.

What happens to my inputs?+

Calculations run in your browser. Results are saved locally only when you add them to My results; favourites and history are also local. Shared links contain your values. The currency tool requests the selected currencies from its rate provider without sending your amount.

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