Sleep Calculator: How to Choose the Right Bedtime


As a Certified Sleep Science Coach, I spend a lot of time offering advice on how to get the best night’s sleep possible. Using a sleep calculator to determinate the perfect amount of sleep is one of the important tools in this regard.

I test countless products to determine if they can help. I offer guides to help match up products with certain types of sleepers, such as the best mattresses for side sleepers. And I offer tips on routines to help get people to sleep as quickly as possible.

However, getting quality sleep is only part of the sleep calculator equation. Getting the right quantity of sleep is also critical to maintaining your health. Why the concept of a sleep calculator is so important.

And one of the most important parts about ensuring you get the proper sleep is setting up a routine bedtime and waking time. Of course, that sounds quite a bit easier than it actually is. After all, the average American isn’t getting enough sleep. In fact, it’s thought that some 40% are getting fewer than six hours a night.

So how can you make sure you’re getting enough sleep? The key is to calculate your ideal bedtime using a proven sleep calculator. So, let’s take a look at how to figure that out.


How Much Sleep Do We Need?

Generally, each person’s sleep needs is different. However, on average, you need somewhere between 7 and nine hours. A commonly used recommendation puts the ideal sleep time at about 7.5 hours—it’s what I shoot for each night.

The recommended sleep calculation for 7.5 hours comes by determining how many sleep cycles we have each night and how long each should take. The average sleep cycle is around 90 minutes and ideally we should hopefully get through about five full sleep cycles. This should allow us to spend adequate time in both slow wave and REM sleep.

To get through about five sleep cycles, we find the average time you should be trying to sleep each night is 7.5 hours (90 min x 5 cycles = 7.5 hours).


The Normal Sleep Cycle Calculator

Sleep Calculator Sleep Cycle

How to Sleep Calculate Your Ideal Bedtime

Once you know how long you need to sleep, you can use the sleep calculator to figure out what time you should actually be going to bed. This is critical to set up your optimal sleep routine. Getting the right amount of sleep is incredibly valuable and this is the ideal first step to take.

The sleep calculation is quite simple. Begin with the time you need to wake up. From there, you’ll count back 7.5 hours to the time you need to sleep. However, don’t stop there. The average person takes 15 minutes to fall asleep once their head hits the pillow and their eyes close, meaning really you need 7 hours and 45 minutes in bed with the lights off. So, work back another 15 minutes to figure out when lights need to go off and you need to get into bed.

The Ideal Bedtime

As we learned above, calculating your ideal sleep quantity is all about determining when to go to bed and when to wake up. The more consistent the bedtime routine are, the better the results of the sleep calculation. Consistency is the key to the ideal sleep and to waking up refreshed every morning.

Done correctly, the sleep calculator will often remove the need for most sleepers to use an alarm clock every morning. When the sleep calculator routine has been put into place, most people will wake up refreshed within a 30 minutes sleep cycle every morning. No need to use an alarm clock, as the body will adjust automatically and wake up during the same sleep cycle each morning.


So it’s a win-win – the right amount of sleep and those slept hours will become a better quality of sleep as well.

A Sample Sleep Calculation

As an example, we wanted to show a rundown of a sleep calculation for the average American adult who has to wake up at 6:30 a.m. each morning. Since we know the average adult should be aiming for 7.5 hours, we calculate our way back to 11:00 p.m. as the time they should be falling asleep. From there we subtract our 15 minutes to give you time to get tired and actually sleeping. That means the ideal bedtime for someone waking up at 6:30 a.m. should be 10:45 p.m. the night before.

The sleep calculator math is simple enough, and all you need to do is do this sleep calculation based on your ideal wakeup time. Once you do that, you should try to put the new timing and sleep routine into place. You’ll be amazed at how much more energy you have each day if you follow a consistent sleep routine.

Also, keep in mind that everyone is different. For example, you may find that it takes you longer to fall asleep once in bed. So, you might adjust the sleep calculation to allow an extra 15 minutes to fall asleep. This is just a baseline—feel free to make alterations to the sleep calculator to make it your own.

One more tip, make sure you try and follow the sleep calculator routine as closely as possible every day, even on weekends. It might be tough not to sleep in once you get the perfect mattress, but the sleep calculation will ensure you’ll get the maximum benefits from your sleep and feel rejuvenated every morning when you awake.