Sleep duration calculator
Enter when you went to sleep and when you woke up to see how long you slept and roughly how many full sleep cycles that is.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter bedtime and wake time.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Duration = wake time - bedtime, plus 24 hours when you wake the next day. Full cycles = whole part of (minutes ÷ 90).
Example
Inputs: Bedtime = 23:00, Wake time = 06:30. Result: Sleep duration: 7:30; Decimal hours: 7.5 h; Against the adult guideline: 7 hours or more.
Limits and caveats
- It counts the time between the two clock times and cannot know how long you took to fall asleep or if you woke in the night.
- The 7-hour guideline is for adults aged 18 to 60; children and teens need more.
- The 90-minute cycle is a rough average that varies between people.
Questions about this tool
How much sleep does an adult need?
The American Academy of Sleep Medicine and the CDC advise adults aged 18 to 60 to sleep 7 hours or more on a regular basis.
Can I use it for a nap?
Yes. Enter its start and end, such as 14:00 to 15:30, which gives 1:30.
What if I went to bed after midnight?
Enter the time as it was, such as 01:15, and the tool counts to your wake time that same morning.