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The Sleep Calculator
That Actually Works

Five calculators in one. Find your ideal bedtime, wake-up time, nap schedule, or baby sleep routine — all based on real sleep cycle science.

Sleep Calculator
Enter your bedtime. Get the best times to wake up feeling fully rested.
What time are you going to sleep?
:
Your age group
Your ideal wake-up times
Based on 90-min sleep cycles · includes 14 min to fall asleep
The Best time matches your recommended sleep for your age. Waking mid-cycle causes grogginess — these times help you avoid it.
Sleep Cycle Calculator
See exactly how many sleep cycles you will get and what happens during each one.
What time are you going to sleep?
:
What time do you need to wake up?
:
Your sleep breakdown
Nap Calculator
Find the best nap length so you wake up alert — not groggy.
What time do you want to start your nap?
:
Choose your nap goal
Your nap end time
Wake Up Time Calculator
Enter when you need to wake up. Get the best bedtimes to hit that alarm feeling great.
What time do you need to wake up?
:
Your age group
Your ideal bedtimes
Go to bed at one of these times to wake up at your chosen hour
The Best time gives you your recommended hours for your age group. Earlier bedtimes give more sleep cycles.
Baby Sleep Calculator
Find the right sleep and nap schedule for your baby based on their age.
Baby's age
Bedtime (when baby usually sleeps at night)
:
Baby's sleep schedule
One Sleep Cycle
90 min
Every cycle moves through light sleep, deep sleep, and REM. Waking at the end of a cycle means you feel rested.
Time to Fall Asleep
~14 min
The average time a person takes to fall asleep after lying down. All results already include this buffer.
Ideal Cycles Per Night
5 – 6
Most adults feel best after 5 to 6 full cycles, which equals roughly 7.5 to 9 hours of sleep.
Best Nap Length
20 or 90 min
A 20-minute nap stays in light sleep. A 90-minute nap completes one full cycle. Avoid 60 minutes — it leaves you groggy.
Common Questions
Why do I feel tired even after 8 hours of sleep?
You most likely woke up in the middle of a sleep cycle. That heavy, foggy feeling is called sleep inertia. It has nothing to do with how many hours you slept — it is about where in the cycle your alarm went off. Use the sleep calculator to find a wake time that lands at the end of a cycle.
How does the sleep cycle calculator work?
It calculates how many full 90-minute cycles fit between your bedtime and wake time, accounting for 14 minutes to fall asleep. It then shows you the exact cycle breakdown so you know whether your schedule gives you enough REM and deep sleep.
What is the best nap length?
A 20-minute nap keeps you in light sleep and leaves you alert afterward. A 90-minute nap completes one full cycle and is great for memory and recovery. Avoid napping for exactly 60 minutes — that puts you in deep sleep, and waking from deep sleep leaves you feeling groggy and disoriented.
How much sleep does a baby need?
Newborns (0–3 months) need 14 to 17 hours across day and night. Infants (4–11 months) need 12 to 15 hours including naps. Toddlers (1–2 years) need 11 to 14 hours. Preschoolers (3–5 years) need 10 to 13 hours. Baby sleep cycles are shorter than adult cycles — roughly 45 to 50 minutes — so babies wake more often between cycles.
Is 6 hours of sleep enough for adults?
For most adults, no. Research consistently shows that 7 to 9 hours is optimal. Regularly sleeping only 6 hours is linked to reduced focus, a weaker immune system, and higher long-term health risks — even if you feel like you have adapted to it over time.
What is REM sleep and why does it matter?
REM stands for Rapid Eye Movement. It is the stage where your brain consolidates memories, processes emotions, and does most of its dreaming. You get more REM in the later cycles of the night. This is why sleeping a full night — rather than short broken stretches — leads to much better cognitive performance the next day.
What is the best bedtime for adults?
Most adults benefit from sleeping between 10 PM and midnight. Your body naturally releases melatonin around 9 to 10 PM as part of your circadian rhythm. Going to bed during this window makes it easier to fall asleep and leads to deeper, higher-quality sleep overall.