Find the best time to sleep or wake up based on sleep cycles.
I want to wake up at
I want to go to sleep at
💡 Each sleep cycle is about 90 minutes. It takes about 15 minutes to fall asleep.
-
⚙️ How It Works
A sleep calculator helps you determine the best time to wake up or go to sleep based on sleep cycles. Sleep occurs in 90-minute cycles, each containing light sleep, deep sleep, and REM sleep. Waking up at the end of a complete cycle (rather than in the middle) leaves you feeling more refreshed. The calculator also accounts for the average 15 minutes it takes to fall asleep.
Wake Time = Bedtime + 15 min (fall asleep) + N × 90 min (cycles) | Recommended: 5–6 cycles (7.5–9 hours) | Minimum: 4 cycles (6 hours)
Editorial Standards
Author
BetterProduct Editorial Team - Editorial standards and multilingual quality review
Reviewed by
Reviewed against public sleep-health guidance and schedule-planning recommendations.
Updated
April 2026
Best used for
Sleep schedule planning and awareness of rest-duration targets.
Languages checked
7 language editions aligned from the same source formulas.
Use Results Responsibly
Use these numbers as screening estimates, not as a diagnosis.
Age, sex, activity, medications, and medical conditions can change the right interpretation.
If you are pregnant, symptomatic, or managing a condition, confirm decisions with a licensed clinician.
Sleep-cycle timing is approximate. Stress, caffeine, illness, and irregular schedules can change how rested you feel.
Use these numbers as screening estimates, not as a diagnosis.
Age, sex, activity, medications, and medical conditions can change the right interpretation.
If you are pregnant, symptomatic, or managing a condition, confirm decisions with a licensed clinician.
❓ FAQ
How many hours of sleep do adults need?
The CDC recommends 7–9 hours for adults aged 18–64, and 7–8 hours for those 65+. Teenagers need 8–10 hours, school-age children 9–12 hours, and toddlers 11–14 hours. Consistently getting less than 7 hours is associated with increased health risks.
What is a sleep cycle?
A sleep cycle lasts about 90 minutes and consists of four stages: N1 (light sleep), N2 (deeper light sleep), N3 (deep/slow-wave sleep), and REM (rapid eye movement, when most dreaming occurs). You typically complete 4–6 cycles per night.
What is REM sleep and why is it important?
REM (Rapid Eye Movement) sleep is the stage associated with vivid dreaming, memory consolidation, and emotional processing. It typically occurs in longer periods in the second half of the night. Cutting sleep short disproportionately reduces REM sleep.
What is sleep debt?
Sleep debt is the cumulative effect of not getting enough sleep. You can't fully 'repay' chronic sleep debt with one long sleep. Consistent sleep deprivation impairs cognitive function, mood, immune response, and metabolism. Prioritize regular sleep over weekend catch-up.