Sleep tool
Sleep Debt Calculator
Add up your weekly sleep debt from the sleep you need and your average on weeknights and weekends, and see how much extra sleep a night helps you catch up.
Nothing you enter leaves your device.
Inputs
Results
Enter values to see your results.
Simple steps
How it works
- 01
Enter how much sleep you need a night (7 or more hours for most adults).
- 02
Enter your average sleep on weeknights and on weekend nights.
- 03
Select Calculate to see your weekly sleep debt and how to catch up.
Good to know
Frequently asked questions
What is sleep debt?
The difference between the sleep you need and the sleep you get, added up over several nights.
How much sleep do I need?
Most adults need 7 or more hours a night; many feel best with 7.5 to 9. Use the amount that leaves you rested.
Can I catch up at the weekend?
Partly. One long lie-in helps less than going to bed a little earlier for several nights, and it can shift your body clock.
Why cap the catch-up at 2 hours a night?
Sleeping much longer than usual is hard and can upset your routine; spreading it out works better.
When should I see a doctor?
If you are often tired despite enough sleep, snore loudly, or cannot sleep well for weeks.
Is anything I enter stored or sent?
No. The calculation runs in your browser. Nothing you type is saved or sent to a server.
How it is calculated
Weekly debt = 5 × (need − weeknight sleep) + 2 × (need − weekend sleep). Catch-up a night = weekly debt ÷ 7, at most 2 hours. Adults are advised to sleep 7 or more hours a night (Watson and colleagues, 2015); lost sleep adds up over days (Van Dongen and colleagues, 2003).
Sources
- Watson NF et al. Recommended amount of sleep for a healthy adult. J Clin Sleep Med 2015;11:591–2
- Van Dongen HPA et al. The cumulative cost of additional wakefulness. Sleep 2003;26:117–26
Last reviewed: October 14, 2026