The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours. In the first example the result is 2.7 hours.
The calculator does not measure melatonin and is not an actigraphy plot. The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours.
Enter data and click Calculate.
The calculator uses the numbers you enter. The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours. In the first example the result is 2.7 hours.
The five form fields are Sleep midpoint weekday vs off-day, Weekend social jet lag, Bright light / screens late evening, Outdoor morning light, and Shift work / recent jet lag burden. Social jet lag means: This is the main result on this page. In the first example it is 2.7 hours. Sleep midpoint weekday vs off-day means: The first form field. It enters the formula or sits beside the result. The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours. Weekend social jet lag means: The second form field. The calculator does not measure melatonin and is not an actigraphy plot.
The second example gives 0.9 hours. The third example gives 5.5 hours. The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours. In the first example the result is 2.7 hours.
The calculator does not measure melatonin and is not an actigraphy plot.
Enter 1.2, 1.5, 6, 20, 2, then click Calculate. A comma in 12.5 is read the same way as a period. Fields on a 0-10 scale are notes and are not the primary result unless this page formula says so.
The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours.
In the first example the result is 2.7 hours. The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours.
2.7 hours
The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours. In the first example the result is 2.7 hours.
0.9 hours
The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours. In the second example the result is 0.9 hours.
5.5 hours
The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours. In the third example the result is 5.5 hours.
In the first example the result is 2.7 hours. The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours.
With the second set of fields the result is 0.9 hours.
With the third set of fields the result is 5.5 hours.
The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours.
The calculator does not measure melatonin and is not an actigraphy plot.
This is the main result on this page. In the first example it is 2.7 hours. The first form field. It enters the formula or sits beside the result. The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours. The second form field. The calculator does not measure melatonin and is not an actigraphy plot.
Yes. 12.5 and 12,5 are read the same way.
No. Fields on a 0-10 scale are notes, unless this page formula counts marked items from them. The primary result comes from this page formula.
Weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum.
No. Evening-light and shift notes do not enter the sum. The calculator does not measure melatonin.
No. You enter the drift hours. The calculator is not a wearable log.
It is the weekend-versus-weekday sleep-hour gap that you enter. The calculator adds it to weekday drift.
Drift values in hours. Light notes are a scale or minutes as the label says and do not change the sum.
The result adds weekday midpoint drift and weekend social jet lag, in hours. Morning light sits beside that sum. Evening-light and shift notes do not change the hours. The calculator does not measure melatonin and is not an actigraphy plot.
Page updated in 2026.
