CalculatorsSleep and recovery

Social Jetlag Calculator

Compare the midpoint of your workday and free-day sleep to describe the timing shift between them.

Your details

Enter only the information needed for this estimate.

Use the time you usually try to sleep, not the time you get into bed.

Use your usual final wake time.

Choose a typical night without a next-morning work or study commitment.

Use your usual final wake time on a day without an alarm when possible.

Calculator entries stay in this browser session to produce this result. This tool does not save them in browser storage.

Complete the fields and select “Compare my sleep timing” to see your estimate.

How social jetlag is calculated

The midpoint of sleep is halfway between bedtime and wake time. The calculator finds that midpoint for a typical workday sleep and a typical free-day sleep, then reports the shortest clock-time difference between them.

For example, sleep from 11 pm to 7 am has a midpoint of 3 am. A later free-day midpoint creates a timing difference even if total sleep duration stays the same.

What the number can help you notice

A large shift may reflect a mismatch between social schedules and preferred sleep timing. Bedtime regularity, morning light, work demands, caring responsibilities, illness, and sleep debt can all influence the result.

Limits of this estimate

  • The estimate uses one typical schedule for each day type and cannot capture night-to-night variation.
  • Time in bed is not always the same as time asleep, especially with long sleep onset or frequent awakenings.
  • Shift work, rotating schedules, naps, and more than two schedule types need a more detailed sleep diary.

Common questions

How should I use this estimate?

Use it as a planning starting point, then compare it with your own experience and any guidance from a qualified health professional.

Is this medical advice?

This calculator provides an educational description of two sleep schedules. It does not measure sleep quality, diagnose a circadian or sleep disorder, or replace individual care.

What happens to what I enter?

The calculator uses the values in your current browser session to produce the result. It does not save them in browser storage.