Terms of Use

Last updated: 13 November 2026

1. Acceptance

By using Sleep Calculator you agree to these terms. If you do not agree, please do not use the site.

2. Free service

Sleep Calculator is free to use. There is no account, no sign-up and no payment. The service is supported by advertising. We may change, add or remove features at any time without notice.

3. What the tool does

Sleep Calculator finds the best bedtimes and wake-up times from 90-minute sleep cycles, and works out how long you sleep between a bedtime and a wake-up time, from the times you type, in your browser. Results are estimates only — sleep cycles average about 90 minutes and vary from person to person. They are not medical advice, and they are for everyday personal use.

4. Not medical advice

Nothing on this site is medical advice. If you have a sleep problem — for example loud snoring, stopping breathing in your sleep, feeling tired all day despite sleeping enough, or not being able to sleep for weeks — please see a doctor. Do not use this site to diagnose or treat any health condition.

5. Lawful use

Use the tool only for lawful purposes. Do not use it to misrepresent a sleep time or a result to anyone else — every result shows how it was worked out so it can always be checked.

6. No warranty

The tool is provided “as is”, without any warranty of any kind. We do not promise that a result is right for your particular purpose — please check important matters yourself.

7. Liability

To the fullest extent allowed by law, Sleep Calculator and its owner are not liable for any direct, indirect or consequential loss arising from the use of this site or its calculations — including any loss from acting on a result shown here.

8. Advertising

The site shows advertising from Google AdSense. Advertisements are provided by third parties; Sleep Calculator is not responsible for their content. You can choose personalised or non-personalised ads with the cookie banner.

9. Changes to these terms

These terms may change from time to time. The new version will be posted on this page with a new “last updated” date. Continued use of the site after a change means you accept the new terms.

10. Contact

Questions about these terms: please use the contact form.