How sleep debt is calculated
The National Sleep Foundation publishes recommended sleep-duration ranges by age group. Sleep debt is the gap between the low end of your age group's recommended range and how much you actually slept.
- recommendedMin — low end of your age bracket's recommended range (h)
- sleptHours — hours you actually slept last night
More detail
Recommended ranges by age (NSF)
0–3 mo: 14–17h · 4–11 mo: 12–15h · 1–2 yr: 11–14h · 3–5 yr: 10–13h · 6–13 yr: 9–11h · 14–17 yr: 8–10h · 18–64 yr: 7–9h · 65+ yr: 7–8h. These are population-level ranges for healthy people without sleep disorders.
Sleep debt accumulates
Sleep debt is measured against a single night here, but the concept compounds: losing 1–2 hours a night for a week adds up to a full night's worth of missed sleep, and it isn't fully repaid by one long lie-in.
Practical tip. If your sleep debt is consistently above 0, try shifting your bedtime earlier by 15–30 minutes at a time rather than sleeping in on weekends — a stable schedule closes debt more reliably than occasional catch-up sleep.
Frequently asked questions
How many hours of sleep should a 30-year-old get?
Adults aged 18–64 are recommended 7–9 hours per the National Sleep Foundation. Enter age 30 and your actual hours slept above to see your exact sleep debt against the 7-hour minimum.
What is sleep debt?
Sleep debt is the gap between the low end of your age group's recommended sleep range and the hours you actually slept, calculated here as max(0, recommendedMin − sleptHours) so it never goes negative.
How much sleep do children need?
Recommended ranges scale down with age: 6–13 year-olds need 9–11 hours and 14–17 year-olds need 8–10 hours, compared to 7–9 hours for adults — enter the child's age above to see their exact bracket.
Do older adults need less sleep?
Slightly — the recommended range for 65+ is 7–8 hours, versus 7–9 for younger adults, mainly reflecting a narrower upper bound rather than a real drop in sleep need.
Can I repay sleep debt by sleeping in on weekends?
Partially, but it doesn't fully cancel out — this calculator measures debt for a single night; chronic short sleep across a week compounds and one long lie-in rarely closes the full gap. Consistent bedtimes work better than catch-up sleep.