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 clock arithmetic around three known inputs: current time, planned bedtime, or desired wake time. This one adds your fall-asleep estimate, checks 6, 5, 4, and 3 approximate cycle windows, and never claims to measure sleep stages.

I am sleeping nowUse your current local time, including late-night date rollover, and see possible wake-up windows.Open calculator →I know my wake-up timeWork backward from your alarm after subtracting fall-asleep time and cycle windows.Open calculator →I know my bedtimeEnter a planned bedtime and count forward after your fall-asleep buffer.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: 7:30 AM - 15 min - (6 x 90 min) = 10:15 PM. Five cycles lands at 11:45 PM; shorter windows are shown only so the tradeoff is visible.

Those times are not measurements of your biology. Read the full methodology and assumptions.

Guides behind the tools

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 cycle assumption fit together. It is strongest when the question is arithmetic: "What are my windows?" not "How will my body respond?"

It cannot measure sleep stages, diagnose a sleep problem, or promise how rested you will feel. Prioritize enough total sleep whenever your schedule allows.

More ways to plan tonight

Sleeping now?Find wake-up options from your current time.Know your alarm?Work backward to a few possible bedtimes.Picked a bedtime?See wake-up times from a set bedtime.Already slept?Estimate how many hours you actually slept.Planning a nap?Nap timing is a planning estimate, not a guarantee that you will wake refreshed.Need to slow down?Build a gentle 10, 20, or 30 minute routine.