Deep Sleep Estimate Calculator

About this calculator

Deep sleep, also called slow-wave sleep or stage N3, is the stage of the sleep cycle marked by the slowest brain waves and the point where you are hardest to wake — it is when the body does most of its physical repair and immune maintenance. In healthy young adults it typically makes up somewhere around 13 to 23% of total sleep time, but that share falls steadily with age, and by the senior years deep sleep can shrink to only a small fraction of what it was in youth.

This calculator applies that age-related decline to your reported total sleep hours to estimate how much of your night is likely spent in deep sleep, which is useful context for anyone reading a sleep tracker's stage breakdown and wondering whether their deep sleep percentage looks typical for their age rather than comparing themselves to a flat, one-size-fits-all target. It is an estimate based on population averages, not a diagnostic measurement — actual deep sleep varies with individual physiology, sleep quality, and can only be measured precisely with polysomnography.

Enter your total sleep hours and your age, and the calculator estimates your deep sleep for the night.