Enter the ideal sleep duration per day and the actual sleep duration per day into the calculator to determine the sleep debt. This calculator can also evaluate any of the variables given the others are known.

Sleep Debt Formula

The following formula is used to calculate the sleep debt.

SD = (ID) - (AD)

Variables:

  • SD is the sleep debt (hours)
  • ID is the ideal sleep duration per day (hours)

What is a Sleep Debt?

Sleep debt is the cumulative effect of not getting enough sleep, which can lead to mental or physical fatigue. It occurs when an individual consistently sleeps less than the recommended amount, typically 7-9 hours for adults. Over time, this lack of rest can lead to a decrease in cognitive function, mood changes, and health problems. Unlike monetary debt, however, sleep debt cannot be fully “repaid” by simply sleeping more on the weekends or days off.

How to Calculate Sleep Debt?

The following steps outline how to calculate the Sleep Debt using the formula: SD = (ID * 7) – (AD * 7).


  1. First, determine the ideal sleep duration per day (ID) in hours.
  2. Next, determine the actual sleep duration per day (AD) in hours.
  3. Multiply the ideal sleep duration per day (ID) by 7 to get the total ideal sleep duration for the week.
  4. Multiply the actual sleep duration per day (AD) by 7 to get the total actual sleep duration for the week.
  5. Subtract the total actual sleep duration for the week from the total ideal sleep duration for the week.
  6. Finally, calculate the Sleep Debt (SD).

Example Problem:

Use the following variables as an example problem to test your knowledge.

ideal sleep duration per day (ID) = 8 hours

actual sleep duration per day (AD) = 6 hours