Privacy Policy

Last updated: September 2026

Summary

All calculations run entirely in your browser. We do not collect, store, process or transmit any of the numbers you enter into our calculators. Your financial data never leaves your device.

What We Collect

Calculator Data

Nothing. Zero. All calculations are performed client-side using JavaScript in your web browser. No data is sent to our servers or any third party.

Analytics

We use Google Analytics to understand which pages are visited and how our site is used. This collects:

  • Pages viewed
  • Approximate location (country/city level)
  • Device type and browser
  • Referring website

Google Analytics does not collect any data you enter into calculators. In the UK, the EEA and Switzerland it sets analytics cookies only after you consent; until then no analytics cookies are stored and Google receives only cookieless measurement signals. You can opt out of Google Analytics using a browser plugin.

Advertising

We display advertisements via Google AdSense. Third-party vendors, including Google, use cookies to serve ads based on your prior visits to this website or other websites. Google's use of advertising cookies enables it and its partners to serve ads to you based on your visits to this site and/or other sites on the internet. You can opt out of personalised advertising at Google Ads Settings, or opt out of some third-party vendors' use of cookies for personalised advertising at aboutads.info. You can read how Google uses information from sites that use its services.

Cookies

We use minimal cookies:

  • Theme preference — stores your light/dark mode choice (localStorage, not a cookie)
  • Analytics cookies — Google Analytics; in the UK, EEA and Switzerland only with your consent
  • Advertising cookies — set by Google AdSense and its partners; in the UK, EEA and Switzerland personalised ads are shown only with your consent

If you visit from the UK, the EEA or Switzerland, Google's consent message asks for your choice on your first visit. It is a consent management platform certified under the IAB Transparency and Consent Framework, and your answer applies to both analytics and advertising. You can change or withdraw it at any time with the "Privacy and cookie settings" link in the site footer.

You can block all cookies in your browser settings without affecting calculator functionality.

Third-Party Services

Your Rights (UK GDPR)

Under UK data protection law, you have the right to:

  • Access any personal data we hold about you
  • Request correction or deletion of your data
  • Object to processing of your data
  • Lodge a complaint with the ICO (ico.org.uk)

Since we don't collect personal data from calculators, there is typically nothing to request. For analytics data, contact us at info@calks.uk.

Data Retention

Since we do not collect personal data from calculator usage, there is nothing to retain or delete. For analytics data collected by Google Analytics, data is retained according to Google's standard retention policy (14 months by default). Advertising data is managed by Google AdSense under their own data retention policies.

Your dark/light theme preference is stored in your browser's localStorage on your device. You can clear it at any time through your browser settings. It is never transmitted to our servers.

Cookie Categories

We classify cookies into three categories:

  • Strictly necessary — None. Our site functions without cookies. Theme preference uses localStorage, not cookies.
  • Analytics — Google Analytics cookies (_ga and _ga_*), set in the UK, EEA and Switzerland only with your consent. These help us understand which calculators are most used so we can prioritise updates and improvements. No personal financial data is included.
  • Advertising — Google AdSense cookies. These may serve personalised or contextual ads. You can opt out via Google Ads Settings or by using a browser extension.

You can block all cookies in your browser settings without affecting any calculator functionality. The calculators work entirely without cookies.

International Transfers

Our site is hosted on Cloudflare Pages, which serves content from edge locations worldwide. Google Analytics and Google AdSense may process data in the United States or other countries. Both Google services operate under appropriate safeguards for international data transfers as described in their respective privacy policies.

Children

Our calculators are suitable for all ages. We do not knowingly collect personal data from children under 13. Since we do not collect personal data from calculator usage, no special provisions are required. If you believe a child has somehow provided personal data to us, please contact us and we will investigate promptly.

Changes to This Policy

We may update this privacy policy from time to time to reflect changes in our practices, technology or legal requirements. The "Last updated" date at the top of this page indicates when the most recent revision was made. We encourage you to review this page periodically. Significant changes will be noted on our Updates page.

Contact the Data Controller

For privacy-related questions, data subject access requests, or to exercise any of your rights under UK GDPR, please contact:

We aim to respond to all privacy enquiries within 30 days, in accordance with UK GDPR requirements. If you are not satisfied with our response, you have the right to lodge a complaint with the Information Commissioner's Office at ico.org.uk.