Schedule a fair multi-city call with the free meeting planner.
Also see the time calculator, time duration calculator, or all calculators.
Free sleep calculator online
Sleep Calculator
Find a bedtime or wake time using 90-minute sleep cycles. Pick an age group for kids, teens, and toddlers. Also try naps, a short quality quiz, and travel or daylight-saving shifts.
Sleep calculator sleep cycles
Find bedtime, wake time & naps
Finish full 90-minute cycles, then add time to fall asleep so you wake at the end of a cycle—not in the middle of one.
Sleep calculator bedtime
Enter when you must get up. You will see lights-out times that line up with sleep cycles.
Sleep calculator best time to wake up
Going to bed now or at a set time? This mode uses complete 90-minute cycles to suggest wake times.
Sleep calculator by age
Pick an age group (infants, toddlers, kids, or teens). You get a bedtime from your usual wake time.
Sleep calculator nap & power nap
Pick a 10, 20, 30, or 90-minute nap end so you do not oversleep into grogginess.
Sleep calculator schedule
Build weekday and weekend times from one wake time, with a small weekend drift so Monday is not a shock.
Sleep calculator quality quiz
A short quiz: hours last night vs your age target, plus caffeine, screens, and a steady schedule. This is not a medical test.
Sleep calculator for travel & daylight savings
Shift bedtime about one hour per day toward the new clock for travel or daylight saving.
How this sleep calculator online works
Most adults cycle through light sleep, deep sleep, and REM about every 90 minutes. Waking at the end of a cycle feels clearer than waking from deep sleep. This tool subtracts (or adds) full cycles plus your fall-asleep buffer—the same idea used in many NHS-style cycle charts.
- Set age, cycle length, and minutes to fall asleep.
- Choose Wake → bedtime or Bed → wake.
- Pick the highlighted slot closest to your age hours, or a shorter night if you must.
- Use Nap, Schedule, Quiz, or Travel when your week isn’t a simple night.
Sleep calculator by age (CDC / NHS-style hours)
Need depends on age. The by-age mode uses public ranges (CDC and NHS-style), not a personal prescription. Use the table with the By age tab.
| Age | Recommended sleep / 24h |
|---|---|
| 0–3 months | 14–17 hours |
| 4–12 months | 12–16 hours (including naps) |
| 1–2 years (toddlers) | 11–14 hours (including naps) |
| 3–5 years | 10–13 hours (including naps) |
| 6–12 years (kids) | 9–12 hours |
| 13–18 years (teens) | 8–10 hours |
| 18–64 years | 7–9 hours |
| 65+ years | 7–8 hours |
Sleep calculator bedtime and best time to wake up
If the alarm is fixed, start from wake time. If you are heading to bed now, start from bedtime. Both modes keep you on 90-minute cycles so the suggested wake time is the end of a cycle, not a random clock mark.
Sleep calculator accuracy
Accuracy depends on your inputs. Someone who falls asleep in 5 minutes vs 40 minutes needs a different lights-out time. Cycle length also varies (often 70–120 minutes). Change the settings at the top rather than treating 90 and 15 as medical facts. This tool does not diagnose insomnia or sleep apnea.
Naps, quality quiz, travel and daylight savings
A 20-minute power nap is often enough for alertness. A 90-minute nap completes one cycle. The quality quiz scores last night vs your age band. For jet lag, shift the clock gradually on the Travel / DST tab. For meeting overlap on long-haul trips, use the time zone meeting planner.
Related calculators
Sleep calculator FAQ
Is this a free sleep calculator online?
Yes. It runs in your browser with no signup: bedtime, wake times, age hours, naps, schedule, quiz, and travel.
How many sleep cycles should I get?
Adults often aim for 4–6 complete sleep cycles (about 6–9 hours plus fall-asleep time). Kids and teens need more; use By age.
Does it follow NHS sleep calculator advice?
Hour ranges and 90-minute cycles match common NHS and CDC-style public guidance. They are not a personal NHS clinical plan.
Can I use it as a sleep calculator for kids or teens?
Yes. Set the age group. School start times matter more for kids and teens than adult 7–9 hour defaults.
What is a power nap in this tool?
The highlighted 20-minute slot is the power nap. Stay under about 30 minutes unless you can spare a full 90-minute cycle.
Scan thousands of cities with our free world clock countdown — clocks update every second.
Compare Eastern Daylight and Central Standard on the est vs cst.