Sleep Calculator
Free sleep calculator — what time should I go to bed? Find bedtimes and wake-up times by 90-minute sleep cycles. Wake up refreshed, not groggy.
Important: By using this page, you agree that calculator or tool results, charts, About explanations, quick tips, and formulas are for informational use only — not professional advice. You assume all risks of relying on them. See the full disclaimer below and our Terms of Service.
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How it works
Choose whether you need to wake up or go to bed at a set time. We count backward or forward in 90-minute sleep cycles so your alarm lands in lighter sleep.
About Sleep Calculator
Informational only — not professional advice. Report an error.
Your alarm goes off at 7:00 and you still feel like you got hit by a truck — even though you were in bed for eight hours. That groggy, heavy feeling often happens when your alarm fires in the middle of a deep sleep cycle instead of near the end when you are in lighter sleep. A sleep cycle calculator does not magic you into perfect rest, but it helps you line up wake times with natural cycle boundaries so mornings hurt less.
Sleep cycles average about 90 minutes from light sleep through deep sleep and REM (rapid eye movement — the dream-heavy stage). Waking between cycles, when you are closer to light sleep, usually feels easier than waking mid-cycle. This tool counts in 90-minute blocks and adds a few minutes for the time it takes you to actually fall asleep after getting into bed.
Pick your scenario: need to wake at a set time (we suggest bedtimes), planning a bedtime (we suggest wake times), or tap "I'm going to sleep now" to use the current clock. For a 7:00 AM alarm, common targets include 9:46 PM for six cycles (about nine hours asleep) or 11:16 PM for five cycles (7.5 hours). This tool only shows options above 7.5 hours asleep — it is a scheduling helper, not sleep or medical advice.
If you are chronically exhausted, talk to a clinician about sleep apnea, insomnia, or other issues no bedtime math can fix.
Small habits amplify the math: dim screens 30–60 minutes before bed, keep a consistent wake time even on weekends, and avoid stacking caffeine late in the day. Pair results with the Calorie Calculator or BMI Calculator if you are rebuilding a broader wellness routine — sleep and nutrition move together even though this page only handles timing.
Advanced options let you tweak fall-asleep minutes if you typically need more than the default 14. Cycle length varies slightly by person; 90 minutes is the standard planning average used by most public sleep calculators. Bookmark your favorite bedtime result so you are not redoing the math every night.
Quick tips
- Try the five- or six-cycle options shown — the calculator does not list bedtimes that would leave 6 hours asleep or less.
- Keep the same wake time seven days a week; your body clock loves predictability more than perfect bedtimes.
- If you snooze repeatedly, set the alarm for the later cycle you actually plan to get up on.
- Persistent fatigue, loud snoring, or gasping at night deserve a doctor visit — not another bedtime tweak.
Formulas
sleepDuration = cycles × 90 minutesbedtime = wakeTime − fallAsleepMinutes − sleepDurationwakeTime = bedtime + fallAsleepMinutes + sleepDuration
Bedtime by wake-up time
- What Time Should I Go to Bed If I Wake Up at 5:00 AM?
- What Time Should I Go to Bed If I Wake Up at 5:30 AM?
- What Time Should I Go to Bed If I Wake Up at 6:00 AM?
- What Time Should I Go to Bed If I Wake Up at 6:30 AM?
- What Time Should I Go to Bed If I Wake Up at 7:00 AM?
- What Time Should I Go to Bed If I Wake Up at 7:30 AM?
- What Time Should I Go to Bed If I Wake Up at 8:00 AM?
- What Time Should I Go to Bed If I Wake Up at 8:30 AM?
- What Time Should I Go to Bed If I Wake Up at 9:00 AM?
Wake-up time by bedtime
- What Time Should I Wake Up If I Go to Bed at 12:00 AM?
- What Time Should I Wake Up If I Go to Bed at 12:30 AM?
- What Time Should I Wake Up If I Go to Bed at 9:00 PM?
- What Time Should I Wake Up If I Go to Bed at 9:30 PM?
- What Time Should I Wake Up If I Go to Bed at 10:00 PM?
- What Time Should I Wake Up If I Go to Bed at 10:30 PM?
- What Time Should I Wake Up If I Go to Bed at 11:00 PM?
- What Time Should I Wake Up If I Go to Bed at 11:30 PM?
Open the main sleep calculator for any custom time.
This tool is part of the free Health & Fitness collection on FindMeTool. Explore more Health & Fitness tools or browse the full tool directory.