Sleep debt calculator.

How sleep debt is worked out

For each night the tool compares your sleep with your target. Net debt is your target times the number of nights, minus the hours you slept, never below zero, so long nights offset short ones. The shortfall figure counts only the short nights and ignores any surplus. Real recovery is not a clean one-for-one swap, so treat both numbers as a guide.

Worked example. Adult target 7 hours. You sleep 6 hours Monday to Friday and 8 hours Saturday and Sunday. Total 46 hours against 49, so net debt is 3 hours. The shortfall on the five short nights is 5 hours and the surplus on the weekend is 2 hours. Spread over 14 nights, 3 hours is 13 extra minutes a night.

CDC recommended sleep by age

Ranges for babies up to preschool include naps. Source (opened 2026-10-05): US CDC, About Sleep, page updated May 15, 2024.

FAQ

What is sleep debt?

Sleep debt is the gap between the sleep you needed and the sleep you got, added up over days. This calculator measures it against the CDC recommended hours for your age group.

How many hours of sleep should I get?

The CDC says adults 18 to 60 need 7 or more hours a night, teens 8 to 10, school-age children 9 to 12, and adults 65 and over 7 to 8. The tool uses the low end of each range as the target.

Can I repay sleep debt at the weekend?

Longer nights offset short ones in the net figure, but how well that repays the debt in real life is not settled by this tool. Steadier nights are the safer aim than a big weekend swing.

Why is net debt smaller than the shortfall?

The shortfall adds up only the short nights. Net debt also credits nights where you slept past your target, so it is the smaller number whenever you had any long nights.

Is a few hours of debt a medical problem?

This tool cannot say. If you are always tired, snore loudly, or sleep much more than you need and still feel unrested, talk to a doctor.

Check your sleep cycle bedtimes to plan the catch-up.