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Sleep Efficiency Calculator

How much of your night is real sleep?

How it is calculated

Sleep efficiency is the share of your time in bed that you actually spent asleep: efficiency = 100 × time asleep / time in bed. Both inputs must be in the same unit (the defaults are minutes, but hours work too since the units cancel). Time in bed must be above zero, time asleep cannot be negative, and time asleep cannot be larger than time in bed; otherwise the tool gives no result. The answer is a percentage with two decimals. 100 % means you fell asleep at once and never woke, and 0 % means no sleep at all. The tool uses only the two totals you enter; it does not look at sleep stages or the number of awakenings.

Worked example

You were in bed for 460 minutes (7 h 40 min) and slept 390 minutes (6 h 30 min). Divide time asleep by time in bed: 390 / 460 = 0.8478. Multiply by 100: the calculator shows 84.78%. The other 70 minutes, about 15 % of the night, were spent awake, falling asleep or lying in bed after waking.

Try this example →

Common mistakes

  • Using total sleep time as the denominator. Efficiency compares sleep with time in bed, including the time you lay awake.
  • Mixing units, such as time asleep in hours and time in bed in minutes. That gives a result near 1 % or an error.
  • Counting the time you were already in bed with the lights on, reading or on your phone, as sleep. Only time actually asleep goes in the first field.
  • Entering time asleep larger than time in bed. That is impossible and the tool gives no result.
  • Judging a single night. One restless night says little; look at an average over several nights.

Sources

About this calculator

Sleep efficiency is the percentage of time spent actually asleep out of the total time spent in bed, calculated as (total sleep time ÷ time in bed) × 100, a core metric used alongside total sleep time and sleep latency in clinical sleep medicine, derived from polysomnography or actigraphy recordings. A sleep efficiency at or above roughly 85% is generally considered a marker of healthy sleep, while sustained values well below that are one of the diagnostic signals used in evaluating conditions like insomnia.

Cognitive behavioral therapy for insomnia (CBT-I), one of the leading evidence-based insomnia treatments, uses sleep efficiency directly to guide sleep-restriction therapy, deliberately limiting time in bed to match actual sleep time and then gradually expanding the window as efficiency improves, and sleep-tracking wearables report a version of this same metric to give users a single number summarizing how restful a night was.

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