Sleep Duration Calculator
Calculate the elapsed time between a bedtime and wake-up time, including overnight windows that cross midnight, with an optional awake-time subtraction.
How long is the time between bedtime and wake time?
Enter a start and end time. If the end time is earlier on the clock than the start time, the calculator treats it as the following day. You can optionally subtract minutes spent awake to estimate sleep within the time window.
Elapsed clock time across midnight
The calculator converts each clock time to minutes after midnight. When the end value is not later than the start value, 24 hours are added to represent an overnight window. Optional awake minutes are then subtracted separately.
Sleep timing is an estimate. A clock-based calculator cannot measure your actual sleep stage or sleep quality.
How to use this calculator
- 1
Enter the bedtime or start time.
- 2
Enter the wake-up or end time and optionally add minutes spent awake.
- 3
Calculate the total time window and estimated sleep after the optional subtraction.
Sleep Duration Calculator FAQ
Can the calculator handle sleep that crosses midnight?
Yes. An end time earlier than the start time is treated as occurring the next day.
What are awake minutes?
They are optional minutes you want to subtract from the overall time window, such as time spent awake after initially going to bed.
Does time in bed equal actual sleep?
Not necessarily. Time in bed and actual sleep can differ, which is why the calculator labels them separately.