cartoon drawing of a calculator

The best sleep calculators

By Jason Wooden, PhD | April 24, 2020

Sleep calculators can be used to help you figure out the right time to go to bed or wake up so that you sleep long enough to get enough sleep cycles to feel refreshed in the morning.

There’s plenty of choices ranging from simple calculators to jet lag prevention calculators.

In this article, you’ll learn about some of the things to keep in mind and a variety of calculators you can use online or through a phone app.

How sleep calculators work

For something that should be pretty simple, a great night of sleep can seem elusive at times.

It’s an unfortunate fact of the modern age that one in three adults in the US and over 30% worldwide struggle with insomnia every night.

That’s a lot of people.

It explains why you and so many others are looking for sleep hacks.

The thing to keep in mind about sleep is that how WELL you sleep is just as important as how LONG you sleep.

To wake up feeling rested and ready for the new day, it’s important to get deep restful sleep.

That means you need to get enough cycles through the four sleep stages:

N1 stage:  between awake and falling asleep

N2 stage onset of sleep

N3 stagedeep restorative sleep

  • tissue growth and repair
  • energy restored
  • growth and development hormones released

REM stage:  rapid-eye-movement and dreams

  • brain and body energy replenished
  • supports daytime performance

I think you can see how important those later stages are since its when your body restores and replenishes itself.

A full sleep cycle through all four stages is roughly 90 minutes long.  Sleep experts say that adults need at least four to five cycles to feel rested.

That works out to about 6 to 9 total hours of sleep for an adult.

So, if your sleep is cut short or fragmented, you won’t get enough full cycles for your body to fully recover.

Sleep calculators are designed to help you figure out the right time to go to bed or wake up so that you get enough complete sleep cycles to feel refreshed in the morning.

They do the mental work for you of counting backwards or forward in sleep cycles to come up with an optimal time to go to sleep or to wake up.

A few things to keep in mind about sleep calculators

A sleep calculator will give you a ballpark estimate:

That’s because in reality sleep cycles are not uniformly 90 minutes throughout the night and can vary from night to night.  Your sleep cycle can even change as you get older.

What’s more, everyone doesn’t have the same sleep cycle times.

So, that’s why you’re just getting an estimate from most of the sleep calculators.

It’s important to sleep when your body’s clock says it’s time to sleep:

Your natural sleep-wake cycle tells your body when it’s time to sleep and when it’s time be awake.  (Sunlight signals your body when to make hormones that regulate sleepiness.)

If the timing is off and you’re trying to sleep when your body says it’s time to be awake, your sleep quality won’t be as good.

We’ve all had the experience of trying to sleep in after a bad night, past the usual wake up time, and it just isn’t quite the same…

It’s recommended that you:

  • stick to a regular routine
  • sleep when it’s time to sleep, get up at regular wake up time
  • avoid bright light in the evening, it can throw off your sleep-wake cycle

Best online sleep calculators

Now, we finally get to the calculators.

Online, you’ll find a lot to choose from with most doing similar things.

Here I’ve listed some that you might find useful for different situations.  Again, keep in mind that what they give you is estimates.

Basic sleep calculator (National Sleep Foundation)

Main features:

  • bedtime, wake up time
  • simple

Get a choice of times (

Main features:

  • bedtime, wake up time
  • gives you a choice of bedtimes and wake up times

Bedtime, wake up time, and naps (

Main features:

  • bedtime, wake up time
  • nap planner

Calculate based on your age (

Main features:

  • bedtime, wake up time personalized for age
  • results broken down to optimize REM and non-REM sleep cycles

Sleep efficiency calculator (Sleepwell)

Main features:  find out how well you’re sleeping

Best phone app sleep calculators


Sleep Calculator Pro

Main features:

  • bedtime and wake up time personalized for age
  • choice of times

Sleepytime Sleep Scheduler

Main features:  bedtime, wake up time

Sleep Cycle – Sleep tracker

Main features:

  • monitors and tracks your sleep to wake you up at the optimal time
  • uses sound to track your sleep cycles

Sleep Time: Cycle Alarm Timer

Main features:

  • monitors and tracks your sleep to wake you up at the optimal time
  • uses sound to track your sleep cycles


Sleep Calculator

Main features:

  • bedtime, wake up time
  • choice of times

Sleep Time – Cycle Alarm Timer

Main features:

  • bedtime, wake up time
  • choice of times

Sleep Away

Main features:

  • bedtime, wake up time
  • set an alarm for a quick power nap

Sleep Time :  Sleep Cycle Smart Alarm Clock Tracker

Main features:

  • monitors and tracks your sleep to wake you up at the optimal time
  • uses sound to analyze your sleep cycles

Best sleep calculators to prevent jet lag

Jet Lag Rooster online calculator

Main features:  gives personalized jet lag plan

Re-Timer online calculator

Main features:  emails you a personalized jet lag plan

Timeshifter phone app

Main features:  gives a personalized jet lag plan based on travel and other factors

Tips to Prevent Jet Lag

Before Travel:

  • Exercise, eat healthy
  • Get plenty of rest
  • Start going to bed later (if traveling west) or earlier  (if traveling east)

During Travel:

  • Change watch to destination local time
  • Avoid large meals, alcohol, caffeine
  • Hydrate
  • Get up and stretch your legs periodically

After You Arrive:

  • Stay up until 10P local time
  • Eat at the appropriate time
  • Hydrate
  • Avoid heavy meals, excess alcohol, caffeine
  • If sleepy, take a short nap

Sources: CDC, National Sleep Foundation

Best sleep calculators for kids

The calculators listed here allow you to enter your child’s age for a better estimate.

American Academy of Sleep Medicine bedtime calculator (bed time only) sleep calculator

Recommended sleep times for kids

4 to 12 months: 12 to 16 hours (including naps)
1 to 2 years: 11 to 14 hours (including naps)
3 to 5 years: 10 to 13 hours (including naps)
6 to 12 years: 9 to 12 hours
13 to 18 years: 8 to 10 hours

Source:  American Academy of Sleep Medicine

Other things besides sleep calculators that can improve your sleep

Your sleep calculator may be a useful tool to improve your sleep, but it’s not the only thing you should be doing.

Bad habits and a bad sleep environment can sabotage your quest for more restful nights.

That’s where sleep hygiene comes into play.  It’s all the things you do during the day, evening and at bedtime that can set the stage for restful sleep.

It focuses on things like your evening routine and bedroom environment.

Depending on where you live, you may need earplugs to block out nuisance noise or a sleep mask to block out excessive light.

Poor sleep hygiene can undercut everything else you do to improve your sleep.

What use is it to go bed on time after a caffeine rich post dinner cup of coffee?  (Even if you’ve been able to get away with this in the past, research suggests it will eventually catch up with you.)

Sleep hygiene tips

  • Keep consistent wake up and sleep times
  • Avoid naps
  • Exercise during the day
  • Avoid large meals, alcohol, or stimulants such as caffeine before bedtime
  • Maintain a bedtime routine to wind down
  • Avoid using TVs, laptops, or other electronics before sleep
  • Keep your sleep environment dark, cool, quiet, and relaxing

Learn more

Lastly, for those nights when find yourself having a hard time falling asleep, there’s a number of tricks you can try:


1. “What Happens When You Sleep?”, National Sleep Foundation website

2. “Enhance Your Sleep Cycles”, Alaska Sleep Clinic website

3. “The ‘Sleep Calculator’ is just unscientific hype”, 2018, Sleep Health Foundation website

4. “Bedtime calculator helps families prioritize healthy sleep”, American Academy of Sleep Medicine website

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Important: is for informational purposes only and is not intended or implied to be a substitute for professional medical advice, diagnosis, or treatment.  Always consult a physician for sleep and health concerns.  See additional information.