GDPR Compliance
Last updated: March 23, 2026
This page explains how CircumferencetoDiameter.net ("we," "us," or "our") complies with the General Data Protection Regulation (GDPR) — the European Union's comprehensive data protection law — and describes the rights available to individuals in the European Economic Area (EEA), the United Kingdom, and Switzerland.
1. Who We Are
CircumferencetoDiameter.net is a free online platform providing circle geometry calculators and educational content. For the purposes of the GDPR, we act as the data controller for any personal data we collect from users of our Website.
Contact for data protection inquiries:
2. What Personal Data We Collect
We minimize data collection to the greatest extent possible. The personal data we may collect includes:
| Data Category | Source | Type |
|---|---|---|
| Contact Information | Contact form (voluntary) | Name, email address, message content |
| Technical Data | Automatic (hosting/analytics) | IP address, browser type, device type, pages viewed |
| Language Preference | User selection | Preferred language setting (stored as cookie) |
Calculator input data is never collected. All calculations run entirely in your browser and no input values or results are transmitted to our servers.
3. Legal Basis for Processing
Under Article 6 of the GDPR, we process personal data based on the following legal bases:
| Processing Activity | Legal Basis | GDPR Article |
|---|---|---|
| Responding to contact form inquiries | Legitimate interest / Consent | Art. 6(1)(a), Art. 6(1)(f) |
| Website analytics (anonymous) | Legitimate interest | Art. 6(1)(f) |
| Website security and performance | Legitimate interest | Art. 6(1)(f) |
| Storing language preference | Consent | Art. 6(1)(a) |
4. Your Rights Under the GDPR
As a data subject in the EEA, UK, or Switzerland, you have the following rights regarding your personal data:
4.1 Right of Access (Article 15)
You have the right to request a copy of the personal data we hold about you, along with information about how it is being processed.
4.2 Right to Rectification (Article 16)
You have the right to request that we correct any inaccurate or incomplete personal data we hold about you.
4.3 Right to Erasure ("Right to Be Forgotten") (Article 17)
You have the right to request that we delete your personal data when:
- The data is no longer necessary for the purpose it was collected
- You withdraw your consent
- You object to the processing and there are no overriding legitimate grounds
- The data has been unlawfully processed
4.4 Right to Restriction of Processing (Article 18)
You have the right to request that we restrict the processing of your personal data in certain circumstances, such as when you contest the accuracy of the data or object to processing based on legitimate interests.
4.5 Right to Data Portability (Article 20)
You have the right to receive your personal data in a structured, commonly used, and machine-readable format and to transmit that data to another controller.
4.6 Right to Object (Article 21)
You have the right to object to the processing of your personal data based on legitimate interests. If you object, we will cease processing unless we demonstrate compelling legitimate grounds.
4.7 Right to Withdraw Consent (Article 7(3))
Where processing is based on your consent, you have the right to withdraw consent at any time. Withdrawal of consent does not affect the lawfulness of processing based on consent before its withdrawal.
4.8 Right to Lodge a Complaint
You have the right to lodge a complaint with your local Data Protection Authority (DPA) if you believe that your data protection rights have been violated. A list of EU DPAs can be found on the European Data Protection Board website.
5. How to Exercise Your Rights
To exercise any of the rights described above, please contact us:
- Email: contact@CircumferencetoDiameter.net
- Subject Line: "GDPR Data Request"
We will respond to your request within 30 days of receipt, as required by the GDPR. In complex cases, this period may be extended by an additional 60 days, and we will notify you of the extension.
To verify your identity, we may ask you to provide additional information before processing your request.
6. Data Retention
We retain personal data only for as long as necessary to fulfill the purposes for which it was collected:
- Contact form data: Deleted within 90 days of inquiry resolution.
- Analytics data: Retained in anonymized form for up to 26 months.
- Cookies: See our Cookies Policy for specific cookie durations.
7. International Data Transfers
Our Website is hosted on Vercel, which may store data on servers located in the United States and other countries. When personal data is transferred outside the EEA, we ensure that appropriate safeguards are in place, including:
- Standard Contractual Clauses (SCCs) approved by the European Commission
- Adequacy decisions where applicable
- Data processing agreements with our service providers
8. Data Protection Measures
We implement appropriate technical and organizational measures to protect your personal data, including:
- HTTPS encryption on all pages
- Minimal data collection practices (data minimization principle)
- Regular review of data processing activities
- Secure data handling procedures
- Privacy-by-design approach in our tool development
9. Cookies and Consent
In compliance with the ePrivacy Directive and GDPR requirements, we inform users about cookie usage and obtain consent where required. For detailed information about the cookies we use, please visit our Cookies Policy.
10. Children's Data
Our Website is not directed at children under the age of 16 (or such lower age as provided by applicable EU/EEA member state law). We do not knowingly collect personal data from children. If you believe a child has provided us with personal data, please contact us immediately and we will delete it.
11. Changes to This Page
We may update this GDPR Compliance page to reflect changes in our data practices or applicable regulations. Any changes will be posted here with an updated "Last updated" date.