Circadian sleep timing analyzer
See whether your sleep timing stays steady across a week, even when some nights cross midnight.
Chronotype calculator
Use your usual sleep times to estimate your sleep midpoint, corrected for catch-up sleep on free days.
Chronotype calculator
Example valuesUse your usual sleep times to estimate your sleep midpoint, corrected for catch-up sleep on free days.
No account needed. Calculations happen in your browser; your entries are not saved or sent to Century.
Example · Corrected free-day midsleep
04:09
This summarizes reported sleep timing, not an internal circadian measurement.
- Social jetlag
- 1.5 h
- Free-day sleep
- 9.0 h
How it’s calculated
The Munich ChronoType Questionnaire uses midsleep on free days, corrected for extra free-day sleep when that sleep is longer than workday sleep. Corrected midpoint = free-day midpoint − (free-day sleep duration − weighted weekly average sleep duration) ÷ 2; no correction is applied when free-day sleep is not longer. This describes habitual sleep timing, not a biological diagnosis or an ideal bedtime.
Reference: Ghotbi et al.: ultra-short MCTQ validation
For general wellness information. This tool does not diagnose health conditions or replace medical advice.
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Chronotype calculator: use your own data
What to enter
Use your usual sleep times to estimate your sleep midpoint, corrected for catch-up sleep on free days.
Free-day sleep timing is less constrained by a work alarm, but extra catch-up sleep can shift its midpoint. The MCTQ correction accounts for part of that difference.
Read the result in context
Free-day midsleep is 04:30. Correct for extra free-day sleep using the weekly average; the result is earlier than 04:30.
It summarizes self-reported habitual sleep timing. Shift work, childcare, travel and irregular schedules can make a single workday/free-day pattern unrepresentative.
Where this estimate stops
Here it is the absolute difference between the midpoints of workday and free-day sleep. It describes a schedule difference, not a medical condition.
See how your sleep timing changes over time in Century.
Frequently asked questions
How can I estimate my chronotype without a wearable?
Enter your usual sleep and wake times on workdays and free days, plus the number of workdays. The calculator finds the middle of free-day sleep and corrects for sleeping longer after workdays.
Why does this use free-day sleep?
Free-day sleep timing is less constrained by a work alarm, but extra catch-up sleep can shift its midpoint. The MCTQ correction accounts for part of that difference.
Is this a clinical circadian-rhythm test?
No. It summarizes self-reported habitual sleep timing. Shift work, childcare, travel and irregular schedules can make a single workday/free-day pattern unrepresentative.
What is social jetlag?
Here it is the absolute difference between the midpoints of workday and free-day sleep. It describes a schedule difference, not a medical condition.