Quick guide
How to use this calculator
- Use the labels and unit notes to enter the requested measurement, date, time, or observation exactly as recorded.
- Check the visible method, population, and unit basis before using the result; switch modes rather than converting values mentally.
- Read the calculation audit and limitations together. The result supports measurement or tracking and does not replace diagnosis, treatment, or urgent medical assessment.
Calculation method
How the social jetlag calculator works
Social jetlag = shortest circular difference between average free-day and workday midsleep.
The output is a descriptive diary or schedule summary. It does not determine sleep quality, a sleep disorder, impairment, or an ideal biological sleep phase.
Worked example
Social Jetlag example
Workday midsleep 03:00 and free-day midsleep 05:00 differ by +2 hours.
Social jetlag = shortest circular difference between average free-day and workday midsleep.
Supported inputs
Precision and limits
Supported purpose
Clock intervals are treated as shorter than 24 hours and do not model daylight-saving or time-zone transitions. Clock outputs round to the nearest minute; an exact 12-hour signed clock difference is displayed as −12 hours by convention. No fixed 90-minute sleep-cycle assumption is used.
Measurement quality
The output is only as reliable as the entered measurement, device, timing, units, and applicable reference population. Recheck unexpected values against the original record.
Clinical boundary
This calculator does not diagnose a condition, choose treatment, change medication, or determine that an urgent symptom is safe to monitor at home. Contact an appropriate health professional or local emergency service when the situation may be urgent.
Privacy
Entered health values and results stay in this browser tab. They are not placed in URLs, analytics, logs, local storage, session replay, or a cloud record by this calculator.