Sleep Calculator
Find the best time to go to bed or wake up based on 90-minute sleep cycles so you wake up refreshed. Free sleep cycle calculator.
✓ 100% free ✓ No sign up ✓ Runs in your browser — nothing uploaded
Go to bed at (6 cycles, 9h)
9:45 PM
Or for 5 cycles (7.5h) 11:15 PM
Or for 4 cycles (6h) 12:45 AM
Or for 3 cycles (4.5h) 2:15 AM
How to use Sleep Calculator
- 1Enter your numbers or dates.
- 2Results update instantly as you type.
- 3Copy the main result with one click.
Questions
Is Sleep Calculator free?
Yes. Sleep Calculator is 100% free with no limits, no watermark, no sign up and no email required.
Is my data sent anywhere?
No. Everything is calculated locally in your browser. Nothing you type is sent to or stored on any server.
Does Sleep Calculator work on my phone?
Yes. Sleep Calculator works in any modern browser on iPhone, Android, Windows, Mac, Linux and Chromebook. No app or install needed.
Do I need to create an account?
Never. There is no sign up, no login, no email and no paywall. Just open the page and use it.
How accurate is it?
Calculations use standard formulas with full floating-point precision. For medical, legal or financial decisions, please confirm with a professional.