Privacy Policy

1. Information we collect

Calculator inputs

When you use the VO2 max calculator, you enter values like age, sex, weight, heart rate, test time, and similar fields. These inputs are processed in your browser. They are not transmitted to our servers or stored anywhere unless you voluntarily submit them to us (for example, by opting in to email your result to yourself).

Email addresses

If you opt in to receive your calculator result by email or subscribe to site updates, we collect your email address and the calculator result values associated with that submission (VO2 max, age, sex, and test method). We use Brevo (Sendinblue SAS) to send these emails and manage the subscriber list. Data is stored on Brevo's infrastructure in the European Union.

Analytics data

We use Google Analytics 4 (GA4) to understand how visitors use the Site in aggregate. GA4 collects standard web-analytics data — page views, referring URL, approximate location (country and region), device type, browser, and anonymized interaction events (e.g., which calculator method you used, which affiliate links you clicked). GA4 may set cookies. See Google's privacy policy for details.

Advertising data

When Google AdSense is enabled, Google and its partners may use cookies and similar technologies to serve ads based on your visits to this Site and other sites. You can control personalized advertising through Google Ads Settings and opt out of third-party cookies via aboutads.info.

Server logs

Our hosting provider (Railway) records basic request metadata — IP address, user agent, request path, timestamp, and response status — for security monitoring and abuse prevention. These logs are retained for a limited period and are not used for marketing.

2. How we use information

• To provide and maintain the calculator and reference content.
• To send you emails you requested (your result, occasional site updates). You can unsubscribe at any time.
• To measure Site usage in aggregate and improve content and features.
• To serve relevant advertising via Google AdSense (when enabled).
• To prevent abuse, fraud, and security incidents.

We do not sell, rent, or trade your personal information. We do not share individual user data with third parties except as needed to provide the services above (e.g., passing your email to Brevo to send you email).

3. Third-party services

The Site relies on the following third-party services. Each has its own privacy policy.

• Brevo (Sendinblue SAS) — email delivery and list management. Privacy policy.
• Google Analytics 4 — usage analytics. Privacy policy.
• Google AdSense — display advertising. How Google uses advertising data.
• Amazon Associates — affiliate links to wearables and training equipment. Clicking an affiliate link redirects you to Amazon, which may set its own cookies. See Amazon's privacy notice.
• Railway — hosting provider. Privacy policy.
• Bunny.net — content delivery network (hero images). Privacy policy.

4. Cookies and similar technologies

The Site uses cookies and similar technologies for analytics (GA4), advertising (AdSense, when enabled), and saving user preferences (e.g., your imperial/metric unit toggle is stored in your browser's local storage). You can block or delete cookies via your browser settings; some features may not work correctly without them.

5. Your rights

GDPR (European Economic Area, UK)

If you are in the EEA or UK, you have the right to access, correct, delete, restrict, and port your personal data, and to object to its processing. To exercise these rights, contact us at the address in Section 9. The legal bases for our processing are consent (email list, advertising cookies) and legitimate interests (anti-abuse monitoring).

CCPA (California)

California residents have the right to know what personal information we collect, to request deletion, and to opt out of the "sale" or "sharing" of personal information. We do not sell personal information as defined by the CCPA. To make a request, contact us at the address in Section 9.

Email opt-out

Every email we send includes a one-click unsubscribe link. You can also request removal from our list by contacting us directly.

6. Children's privacy

The Site is not directed to children under 13 (or under 16 in the EEA/UK). We do not knowingly collect personal information from children. If you believe a child has given us personal information, please contact us and we will delete it.

7. Data retention

Email addresses on our Brevo list are retained until you unsubscribe. Aggregate analytics data is retained per Google's default GA4 settings (14 months for user-level data, indefinitely for aggregated reports). Server logs are retained for up to 30 days.

8. Security

We use reasonable technical and organizational measures to protect your information, including HTTPS for all traffic and access controls on vendor platforms. No system is perfectly secure; you use the Site at your own risk.

9. Contact

Questions, requests, or complaints about this Privacy Policy can be sent to [email protected]. We aim to respond within 30 days.

10. Changes to this policy

We may update this Privacy Policy from time to time. When we do, we will revise the "Effective date" at the top. Material changes will be announced on the Site and, where required, by email.