Sleep Calculator
Estimate bedtime or wake-up times from a target schedule. This calculator uses a simple sleep-cycle planning model rather than measuring your actual sleep.
Calculate sleep timing
Choose whether your known time is bedtime or wake-up time.
How the sleep calculator works
The tool works backward or forward from a time you already know. It checks four, five, and six estimated 90-minute cycles and adds a small sleep-onset allowance.
Real sleep cycles are not fixed at exactly 90 minutes. They can vary across people and across the same night, so use these results as planning options rather than a precise biological measurement.
Calculating sleep for a healthier schedule
Calculating sleep timing works best when you start with enough sleep opportunity. Adults commonly need at least seven hours, while children and teenagers generally need more. Your work, school, health, and individual sleep needs also matter.
The phrase sleep calculating describes a planning process, not a clinical measurement. A calculator can suggest a schedule, but it cannot tell you exactly how much REM or deep sleep you will get.
Related sleep tools
Bedtime Calculator · Wake-Up Time Calculator · Sleep Cycle Calculator · Sleep Duration by Age