Sleep Calculator — Best Bedtime & Wake-Up Times

Find the best time to fall asleep or wake up based on natural 90-minute sleep cycles, so you wake between cycles instead of in the middle of one.

Wake-up time

Next step with AI

Got your sleep schedule. Build the rest of your wellbeing routine with AI:

Sleep Improvement Advisor
Get a personalised plan to fix your sleep — root causes, evening routine, light, caffeine cutoffs and a 14-day plan.
Habit Builder
Get a personalised plan to build any habit in 30 days — cue, minimum viable version, environment design and a relapse protocol.
Stress Level Analyzer
Answer a few questions and get a personalised stress assessment, root causes, a 7-day reset plan and red flags. Free and private.

What it does

Sleep Calculator works backwards from your wake-up time (or forwards from now) in 90-minute cycles, accounting for the 15 minutes the average person needs to fall asleep, and suggests bedtimes that align with the end of a complete sleep cycle.

When to use it

Use it the night before an early flight, exam, big meeting — or whenever you want to wake up refreshed instead of groggy.

Benefits

Based on the 90-minute REM cycle
Two modes: wake-up time or sleep-now
Highlights 5–6 cycle sweet spots
Accounts for falling-asleep time

Example

Want to wake at 6:30 AM? The calculator suggests bedtimes of 9:15 PM or 10:45 PM for a full 6 or 5 sleep cycles.

Frequently asked questions

Why 90 minutes?: A typical sleep cycle (light → deep → REM) lasts about 90 minutes. Waking between cycles feels easier than waking mid-cycle.
Why subtract 15 minutes?: Research suggests the average healthy adult takes 10–20 minutes to fall asleep. We use 15 as a middle ground.
Is this medical advice?: No — it's a general guide based on common sleep science. Consult a doctor for sleep disorders.

Related tools

Browse all Calculators →