Privacy Policy
Last Updated: May 6, 2026
1. Introduction
OneCalc ("we", "us", "our") is a free online collection of calculators operated by Arthurs, LLC. This Privacy Policy explains what information we handle when you visit our website, how we use it, and the choices you have. By using OneCalc you accept the practices described below.
2. Information We Collect
We do not require an account and we do not collect personally identifiable information (such as your name, email address, or phone number) unless you voluntarily send it to us through the contact form. Every calculation you perform runs locally inside your browser; the values you enter are never transmitted to our servers.
3. Local Storage and Cookies
OneCalc uses your browser's local storage to remember preferences such as your preferred unit system (Metric/Imperial), theme, language, recently used currencies, and a private history of recent calculations. This data stays on your device and is never sent to us. We also use a small first-party storage entry to record your cookie consent choice. For audience measurement we use Cloudflare Web Analytics, which is cookieless (see Section 4). Advertising cookies will only be used in the future and only with your consent (see Section 5). You can clear local storage and cookies at any time from your browser settings.
4. Audience Measurement
We use Cloudflare Web Analytics to understand which calculators and pages are popular. It is cookieless: it does not set any cookies, does not assign an identifier to your browser, and does not track you across sites. We see only aggregated metrics — page views, referrers, browser and operating system family, and country. We cannot identify individuals from this data. Because no cookies or identifiers are involved, EU/UK ePrivacy law does not require your consent for this measurement. Cloudflare's privacy practices are available at https://www.cloudflare.com/privacypolicy/.
5. Advertising (Planned Future Use)
We are preparing to display advertisements served by Google AdSense. Once activated, Google and its partners may use cookies — including the DoubleClick DART cookie — and similar technologies to serve ads based on your prior visits to OneCalc and other websites. Where the law requires (notably in the EEA, the UK, and California), personalized ads will be shown only after you have given specific consent through our cookie banner; otherwise we will request non-personalized ads. This Policy will be updated when advertising goes live.
6. Your Choices and Opt-Out
You can manage advertising consent at any time through the cookie banner that appears on your first visit, and via the "Cookie Settings" link in the footer. You can also clear cookies and local storage from your browser, install tracking-blocker extensions, and opt out of personalized advertising directly via Google Ad Settings (https://adssettings.google.com/), the Network Advertising Initiative (https://optout.networkadvertising.org/), the Digital Advertising Alliance (https://www.aboutads.info/choices), or Your Online Choices in Europe (https://www.youronlinechoices.eu/). Audience measurement (Cloudflare Web Analytics) is always active because it is cookieless and aggregated; disabling cookies in your browser does not affect it. Disabling advertising cookies does not affect calculator functionality.
7. Rights in the EEA and the United Kingdom (GDPR)
If you are located in the European Economic Area, the United Kingdom, or Switzerland, you have the right to access, rectify, erase, restrict or object to the processing of your personal data, and the right to data portability. Because we hold no account-level data about you, most requests can be satisfied simply by clearing your local storage. For other requests, contact us at contact@onecalc.app. You also have the right to lodge a complaint with your local data protection authority.
8. Rights of California Residents (CCPA / CPRA)
California residents have the right to know what personal information is collected, to request deletion, and to opt out of the "sale" or "sharing" of personal information for cross-context behavioral advertising. We do not sell personal information for money. Once advertising is enabled, you can refuse the sharing of information for personalized advertising through our cookie banner; we will honor a Global Privacy Control (GPC) signal sent by your browser as such an opt-out.
9. Children's Privacy
OneCalc is a general-audience site and is not directed at children under the age of 13 (or the equivalent minimum age in your jurisdiction). We do not knowingly collect personal information from children. If you believe a child has provided us with personal information, please contact us and we will delete it.
10. Data Retention
Information you send through the contact form is kept only as long as necessary to respond to your inquiry, and is then archived or deleted. Aggregate audience metrics from Cloudflare Web Analytics are retained for up to six months and contain no cookies or individual identifiers.
11. Changes to This Policy
We may update this Privacy Policy from time to time — for example, to reflect new features such as the launch of advertising, a change of analytics provider, or changes in the law. Material changes will be highlighted on this page and the "Last Updated" date above will be revised. Please review the policy periodically.
12. Contact Us
If you have any questions about this Privacy Policy or our data practices, please email us at: