Privacy
Short version: the calculators run on your device. What you type into them is never sent to us.
What we store
To save you time, your browser remembers the last times you entered, using local storage on your own device. You can clear it at any time by clearing your browser's site data. It is never sent anywhere. We also remember whether you chose light or dark mode.
What we don't do
- We don't ask for an account or email.
- We don't sell data.
- We don't use advertising trackers or cookies on this site.
Links to other sites
When you follow a link to another site, including our partner Titan Recovery, that site's own privacy policy applies. Links to Titan Recovery include a tag showing the visit came from SleepTimeCalc, but no personal information.
Hosting
This site is hosted by Vercel, which keeps standard server logs (such as IP address and pages requested) for security and reliability.
Our free tools
Every one of them is completely free.
- Sleep CalculatorBest bedtime or wake-up time, based on 90-minute sleep cycles.
- Nap CalculatorWhen to set your alarm for a power nap or a full-cycle nap.
- Sleep Debt CalculatorHow much sleep you owe this week, and how to pay it back.
- Caffeine Cutoff CalculatorHow much caffeine is still in you at bedtime, and your latest cup.
- Sleep Needs by AgeRecommended hours for every age, from newborns to over-65s.
- Sleep Efficiency CalculatorWhat share of your time in bed you actually spend asleep.
- Shift Work Sleep CalculatorWhen to sleep and stop caffeine around any shift, including nights.
- Jet Lag CalculatorDays to adjust, plus a shift-before-you-fly schedule.