Sleep Calculator — Bedtime, Wake Time & Duration
Plan bedtime from a required wake time, compare wake-time options from bedtime, or measure an overnight sleep window with latency, age guidance and a visual timeline.
Sleep schedule planner
Plan time in bed, compare duration guidance, and explore cycle-length scenarios without claiming an exact REM wake-up.
Overnight timeline
Bedtime calculator
Choose a required wake time and desired sleep duration. The planner subtracts both sleep time and your estimated sleep latency to find when to get into bed.
Sleep-cycle scenarios
NHLBI says sleep cycles usually restart every 80–100 minutes and people commonly have four to six cycles. The adjustable interval is a planning aid, not a measurement of your personal stages.
Sleep duration by age
CDC guidance changes by age: teenagers generally need 8–10 hours, adults 18–60 need at least 7 hours, and younger children need more, often including naps.
Duration is not sleep quality
Time in bed does not prove uninterrupted or restorative sleep. Persistent difficulty sleeping, excessive sleepiness, snoring, or breathing concerns deserve professional evaluation.
Frequently asked questions
Is every sleep cycle exactly 90 minutes?
No. NHLBI gives a broader 80–100 minute range, and cycles change across a night. Ninety minutes is only an editable planning midpoint.
Does the result include time to fall asleep?
Yes. Bedtime planning adds your latency before the desired sleep duration starts.
What happens when bedtime is after midnight?
All calculations wrap safely across midnight and label the result as today or tomorrow when useful.
Can this diagnose insomnia or sleep apnea?
No. It performs time arithmetic and shows public duration guidance; it cannot assess sleep quality or diagnose a disorder.
Sources
CDC: About SleepNHLBI: Sleep StagesAASM: Adult Sleep Duration
