Privacy Policy

Last updated: April 2026

We do not collect, transmit, or store any personal data. Bedtime Calculator works entirely on your device.

Who we are

Bedtime Calculator is a free sleep cycle calculator available at bedtimecalculator.app and as a Chrome browser extension. It helps you find the best time to go to sleep based on 90-minute sleep cycles.

What data we collect

None. We do not collect names, email addresses, IP addresses, location data, or any other personally identifiable information.

We do not use analytics tools, advertising networks, or any third-party tracking scripts.

What stays on your device

The website stores no data. It uses localStorage only if you choose to save a bedtime reminder — this data never leaves your browser.

The Chrome extension stores two small preferences locally using chrome.storage.local:

Your chosen time format (AM/PM or 24h)
Your chosen calculator mode (wake-up time or bedtime)

These preferences are stored only on your device and are never sent to any server.

Notifications and alarms

If you set a bedtime reminder, the website uses the browser Notification API to show a local notification at the time you selected. The Chrome extension uses the Chrome Alarms API for the same purpose. In both cases, no data about your sleep schedule or reminder times is transmitted anywhere.

Cookies

We do not use cookies.

Third-party services

The website may display Google AdSense advertisements. Google may use cookies to show relevant ads based on your browsing history. You can opt out at adssettings.google.com. We have no access to any data Google collects for this purpose.

Apart from optional advertising, we use no other third-party services, CDNs, or external scripts.

Chrome extension permissions

The Bedtime Calculator Chrome extension requests the following permissions, each used solely for its stated purpose:

alarms — to schedule your bedtime reminder at the exact time you choose
notifications — to show a system notification when your reminder fires
storage — to remember your time format and mode preference
tabs — to open bedtimecalculator.app when you click "Full site" or the notification

Children's privacy

Bedtime Calculator does not knowingly collect any information from children under 13. The service contains no registration or data entry forms.

Changes to this policy

If we ever change this policy in a meaningful way, we will update the date at the top of this page. Since we collect no data, changes would only occur if we add new features that require them.

Contact

If you have questions about this privacy policy, please contact us at hello@bedtimecalculator.app.