Health Calculators
Sleep efficiency calculator.
Enter when you got into bed, when you got up, and how long you were awake in between. Get your sleep efficiency: the share of your time in bed that you were asleep. Runs in your browser; nothing is sent or stored.
Your night
Sleep efficiency
Fill the form and press Calculate efficiency.
How sleep efficiency is worked out
Sleep efficiency = time asleep ÷ time in bed × 100. Time in bed runs from getting into bed to getting out. Time asleep is that, minus the time it took to fall asleep, minus time awake during the night, minus time awake after your final waking. Times past midnight are handled automatically.
Worked example. In bed 10:30 PM, out at 6:30 AM: 480 minutes. You took 20 minutes to fall asleep, were awake 30 minutes during the night, and lay awake 10 minutes before getting up. Asleep: 480 − 60 = 420 minutes. 420 ÷ 480 = 87.5%.
Bands used here
Your estimates of when you fell asleep are rough, and people often misjudge them. Sleep apps and watches are estimates too. Only a sleep study measures sleep directly. Source (opened 2026-10-05): Sleep Foundation, Sleep Restriction Therapy (formula as average time asleep divided by average time in bed times 100; the 85% and 90% thresholds), updated August 3, 2026. Sleep restriction itself is a therapy to do with a clinician, so this tool does not suggest changing your bedtime.
FAQ
What is a good sleep efficiency?
The Sleep Foundation uses 85% and 90% as thresholds in its sleep restriction guidance: below 85%, 85% to 90%, and above 90%.
How do I calculate sleep efficiency?
Divide the time you were asleep by the time you were in bed, then multiply by 100. For example, 7 hours asleep out of 8 hours in bed is 87.5%.
Does sleep efficiency tell me if I slept enough?
No. It measures how much of your time in bed was spent asleep, not how many hours you slept. Use the sleep debt calculator for hours.
Is my watch or app accurate for this?
Wearables estimate sleep from movement and heart rate, and they can be wrong about when you were awake. Treat the result as a trend, not a measurement.
Should I cut my time in bed if my efficiency is low?
Not on your own. Restricting time in bed is a therapy for insomnia that is done with guidance, because it can leave you short of sleep. Talk to a doctor.
Also see the sleep debt calculator.
Disclaimer
General information, not medical advice and not a diagnosis. Self-reported sleep is approximate. If you struggle to fall asleep or stay asleep, or feel unrefreshed most days, see a doctor.