Sleep Calculator
Find the best bedtime or wake-up time based on 90-minute sleep cycles so you wake up refreshed.
100% free No signup Private & offline-ready Works in your browser
About the Sleep Calculator
Sleep happens in cycles of about 90 minutes. Waking up at the end of a cycle, rather than in the middle of deep sleep, helps you feel less groggy. Adults usually need 5–6 cycles (7.5–9 hours) per night.
Frequently asked questions
Is the Sleep Calculator free?
Yes. The Sleep Calculator on Apex Tool Station is 100% free with no signup and no watermark. Browser tools have no usage limits.
Are my files or data uploaded to a server?
No. Everything runs locally in your browser using JavaScript. Your files and text never leave your device, which makes it safe for private documents.
Does it work on mobile?
Yes. The tool works on any modern browser on Android, iPhone, Windows, Mac and Linux.