Bedtime and wake-up planning
Sleep calculator
Choose the calculator that matches what you know: the current time, your alarm time, or a planned bedtime.
Quick answer:a sleep calculator handles the time arithmetic around an adjustable fall-asleep estimate and several approximate cycle windows. It cannot measure a person's actual sleep stages.
I am sleeping nowUse your current local time and see possible wake-up windows.Open calculator →I know my wake-up timeWork backward from your alarm to compare possible bedtimes.Open calculator →I know my bedtimeEnter a planned bedtime and count forward to wake-up options.Open calculator →
Worked example
Wake at 7:30 AM with 15 minutes to fall asleep
Working backward with the site's 90-minute planning estimate produces options such as 10:15 PM for six cycles or 11:45 PM for five cycles. The calculator also displays shorter windows for context.
Those times are not measurements of your biology. Read the full methodology and assumptions.
Limits
What a sleep calculator can and cannot tell you
A calculator can show how a chosen bedtime, wake-up time, fall-asleep estimate, and simple cycle assumption fit together.
It cannot measure sleep stages, diagnose a sleep problem, or promise how rested you will feel. Prioritize enough total sleep whenever your schedule allows.