Sleep Calculator

Find ideal bedtimes based on 90-minute sleep cycles so you wake up refreshed

About this calculator

The Sleep Calculator helps you find the best bedtime or wake-up time based on 90-minute sleep cycles. Getting up between cycles instead of in the middle of one leaves you feeling more refreshed and alert. Enter your desired wake-up time or bedtime to see sleep-cycle-aligned suggestions.

How to use the Sleep Calculator calculator

  1. Enter your values into the input fields.
  2. Read the result — it updates instantly as you type.
  3. Adjust the inputs to compare scenarios.
  4. Copy the page URL to share the exact calculation.

Common examples

  • Wake at 7:00 AM → suggested bedtimes: 11:00 PM (6 cycles), 12:30 AM (5 cycles), 4:00 AM (2 cycles), 5:30 AM (1 cycle)
  • Bedtime 11:00 PM → suggested wake times: 12:30 AM (1 cycle), 2:00 AM (2 cycles), 5:30 AM (5 cycles), 7:00 AM (6 cycles)
  • Need 7.5 hours of sleep → 5 complete sleep cycles; sleep at 11:00 PM, wake at 6:45 AM
  • Power nap: 1 sleep cycle = 90 min; 2 cycles = 3 hours for a restorative rest
  • Teen needing 9 hours: bedtime 9:30 PM → wake at 6:45 AM (6 complete cycles)

Frequently asked questions

How does the Sleep Calculator calculator work?

Enter your numbers and the calculator applies the standard formula for this everyday task, showing the result and how it was reached. It handles the unit and rounding details so you do not have to.

When would I use the Sleep Calculator calculator?

Whenever this comes up in daily life — planning, shopping, home projects, travel or work — and you want a quick, dependable answer instead of estimating or working it out by hand.

How accurate are the results?

The math runs at full precision internally and only the displayed value is rounded for readability. For real-world use the practical limit is the accuracy of the numbers you enter, not the calculation.

Can I share a specific calculation with someone else?

Yes. Every value you enter updates the URL, so copying the address bar and sharing the link reopens the exact same calculation for whoever clicks it.