Find the best bedtimes and wake times based on 90-minute sleep cycles, so you wake up refreshed
When should you go to bed so you wake up right at the end of a sleep cycle
When to wake up if you sleep complete cycles
💤 One sleep cycle lasts about 90 minutes, and it takes about 15 minutes to fall asleep — this tool already allows for that. Waking at the end of a cycle feels more refreshed than waking mid-cycle.
Sleep Calculator is a free online tool by HubTools — Find the best bedtimes and wake times based on 90-minute sleep cycles, so you wake up refreshed. Use it instantly in your browser: no installation, no signup.
Privacy matters — this tool runs 100% in your browser. Your files and data are never uploaded to any server; close the tab and everything is gone.
Enter your details such as weight, height, age, or an important date
Choose the options that match your situation, such as your weekly activity level
Click calculate to see the result and all related values
Use the result to adjust your routine, and consult a professional for further advice
Yes. Sleep Calculator by HubTools is 100% free, with no signup and no usage limits.
No — Sleep Calculator runs entirely in your browser. Your files and data are never uploaded to any server.
No account required. Just open the page and start using it immediately — no personal information needed.