Sleep debt calculator
Enter the hours you slept on each of the last 7 nights and how much sleep you need. The calculator adds up the shortfall and shows extra-sleep nights separately.
Weekly sleep debt calculator
Sleep debt this week: 1.5 hours
- Nights logged 6 of 7
- Nights under your need 2
- Nights over your need 3 (3.5 hours extra)
- Average on logged nights 7 h 20 min
Extra sleep on some nights is shown separately and isn’t subtracted from the debt: research suggests a lie-in may not fully make up for short nights [1][2].
This calculator gives general estimates based on average 90-minute sleep cycles. It isn’t medical advice. If you have ongoing trouble sleeping, loud snoring, or daytime sleepiness, talk to a doctor.
How accurate is this? It’s simple arithmetic on the numbers you enter. It can’t measure how well you slept, and recommended ranges are averages: individual needs vary [3].
How the sleep debt is calculated
For each night you log, the calculator compares the hours slept with your nightly need. If you slept less, the difference is added to your debt. If you slept more, that night is counted as an extra-sleep night, but the extra hours are not subtracted from the debt. Blank nights are ignored.
| Night | Slept | Shortfall | Extra |
|---|---|---|---|
| 1 | 6.5 h | 0.5 h | – |
| 2 | 7 h | – | – |
| 3 | 6 h | 1 h | – |
| 4 | not logged | – | – |
| 5 | 7.5 h | – | 0.5 h |
| 6 | 9 h | – | 2 h |
| 7 | 8 h | – | 1 h |
In this example the sleep debt is 1.5 hours over 6 logged nights, and three nights went over the 7-hour need by 3.5 hours in total. Those are reported side by side, not netted against each other.
Why surplus sleep isn’t netted
It’s tempting to think a long lie-in on Saturday “pays back” a week of short nights. The evidence is less reassuring. NINDS notes that many people feel they can catch up on missed sleep at the weekend, but depending on how sleep-deprived they are, sleeping longer may not be enough to replace the sleep they’ve missed [1].
In a controlled laboratory study, young adults who slept 5 hours a night during the week and then slept as much as they liked at the weekend did not avoid the metabolic effects of short sleep: the authors concluded that weekend recovery sleep is not an effective strategy to prevent metabolic dysregulation associated with recurrent insufficient sleep [2]. Another laboratory study estimated that just 1 hour of potential sleep debt took four days to recover [4].
So the calculator doesn’t promise a “repayment plan”. It shows the shortfall honestly and leaves the conclusion to the research: regular, sufficient sleep is what counts.
Choosing your sleep need
The age-group menu uses the low end of the range recommended for each age group in the CDC table, which draws on the American Academy of Sleep Medicine, the Sleep Research Society and the National Sleep Foundation [5]. For adults that’s 7 hours: the AASM and Sleep Research Society recommend 7 or more hours a night on a regular basis [6]. NHLBI notes that sleeping more than 9 hours is not necessarily harmful and may help people recovering from sleep deprivation [3]. If you know you need more than the minimum, choose “My own number”.
Children’s ranges are per 24 hours and include naps for younger ages [7], so for a child you’d log total sleep including naps. See the full sleep-by-age chart.
What to do with the result
- Look for a pattern. One short night is different from five. The “nights under your need” count shows how regular the shortfall is.
- Move bedtime, not just the alarm. Use the bedtime calculator to find a bedtime that gives you 5 or 6 full cycles before your alarm.
- Keep the schedule steady. Going to bed and getting up at the same time every day is one of the habits CDC lists for better sleep [5].
- Check what keeps you up. Caffeine late in the day can disturb sleep [8]; try the caffeine cutoff calculator.
When it’s more than a busy week
If you’re short on sleep even though you give yourself enough time in bed, or you feel tired after what should be enough sleep, that is worth raising with a healthcare provider. CDC lists trouble falling asleep, repeatedly waking during the night and feeling sleepy even after enough sleep as signs of poor sleep quality [5].
Related guides
Find out how much sleep you need and what happens across a night of sleep.
- Sleep cycles explained: the stages, REM, and why cycles vary.
- How much sleep do you need by age?: the recommended hours for every age group.
- Sleep FAQ: 26 common questions, answered with sources.
Frequently asked questions
What is sleep debt?
The gap between the sleep you need and the sleep you actually get, added up over several nights. This calculator adds up the shortfall over the last 7 nights.
Can you pay back sleep debt?
Not simply hour for hour. NINDS notes that sleeping longer on weekends may not be enough to replace the sleep you’ve missed [1], and a laboratory study found weekend recovery sleep did not prevent the metabolic effects of repeated short sleep [2].
How long does it take to recover from sleep debt?
There is no fixed answer. In one laboratory study, recovering from just 1 hour of potential sleep debt took four days [4]. The practical takeaway is a regular schedule with enough sleep every night.
Why don’t extra hours cancel out short nights?
Because research doesn’t support simple netting. Weekend lie-ins may not fully make up for missed sleep [1][2], so the calculator shows nights over your need separately instead of subtracting them.
What number should I use for my sleep need?
Use the age-group setting (it takes the low end of the recommended range, for example 7 hours for adults [5]), or enter your own number if you know you need more.
What if I don’t remember how long I slept?
Leave that night blank. Blank nights are skipped, not counted as zero.
Is my sleep data saved?
Your entries are saved only in this browser on this device so they’re there next time. They are never sent to us. Use “Clear saved entries” to delete them. See the privacy policy.
Should I see a doctor about sleep debt?
If you regularly can’t get enough sleep, or feel sleepy during the day despite enough sleep, talk to a healthcare provider [5].
Sources
- NINDS (NIH): Brain Basics: Understanding Sleep. February 25, 2025. Accessed October 21, 2026.
- PubMed: Ad libitum Weekend Recovery Sleep Fails to Prevent Metabolic Dysregulation… (Depner et al., Curr Biol 2019;29(6):957–967). 2019. Accessed October 21, 2026.
- NHLBI (NIH): How Much Sleep Is Enough?. March 24, 2022. Accessed October 21, 2026.
- PubMed: Estimating individual optimal sleep duration and potential sleep debt (Kitamura et al., Sci Rep 2016;6:35812). 2016. Accessed October 21, 2026.
- CDC: About Sleep. May 15, 2024. Accessed October 21, 2026.
- AASM / SRS: Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the AASM and Sleep Research Society (Watson et al., J Clin Sleep Med 2015;11(6):591–592). 2015. Accessed October 21, 2026.
- AASM: Recommended Amount of Sleep for Pediatric Populations: A Consensus Statement of the American Academy of Sleep Medicine (Paruthi et al., J Clin Sleep Med 2016;12(6):785–786). 2016. Accessed October 21, 2026.
- PubMed: Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed (Drake et al., J Clin Sleep Med 2013;9(11):1195–1200). 2013. Accessed October 21, 2026.
Last reviewed by the CycleRest team (sources re-checked; no medical reviewer). Editorial policy