Privacy Policy

Who We Are

One Calculator is a free collection of online calculators published at https://onecalculator.app. It is operated by an independent developer based in India. Throughout this policy, "we", "us", and "our" refer to One Calculator; "you" refers to anyone who visits the site.

We built One Calculator as a static website. There is no server-side application, no database, no user accounts, and no place for us to store anything you type. This policy explains exactly what that means in practice, what we do and do not collect, and what third parties involved in the site may collect.

If you have questions about anything here, write to us at privacy@onecalculator.app.

The Short Version

• Your calculator inputs — dates, height, weight, and everything else — are processed entirely inside your browser and are never sent to us or anyone else.
• We have no accounts, no sign-up, no login, no newsletter, and no forms that submit data anywhere.
• We do not run analytics and we do not set cookies of our own.
• Your saved calculation History and your settings live in your browser's local storage, on your own device, and you can clear them at any time.
• Our hosting provider automatically records basic technical request logs, including IP addresses.
• We plan to display ads through Google AdSense. Google and other ad vendors may set and read cookies and use identifiers in your browser. Opt-out links are in the advertising section below.

What This Site Does, and Where Your Data Goes

One Calculator offers an Age Calculator and a BMI Calculator. Every calculation runs as JavaScript in your own browser.

When you enter your date of birth, your height, or your weight, that information stays on your device. It is not transmitted to us, it is not written to any database, and it never appears in a network request. We have no server that could receive it, because the site is exported as static files and served as-is.

This is not a promise we ask you to take on faith — you can confirm it. Open your browser's developer tools, switch to the Network tab, and use any calculator on the site. You will see the page's own files load, and nothing carrying your input leave your browser.

We also do not transmit any calculator input — including any health-related figure such as height, weight, or BMI result — to advertising systems, and we do not use anything you enter to target ads.

Information We Do Not Collect

To be specific about the things many privacy policies claim and we do not do:

• We do not collect your name, email address, phone number, or postal address. There is no form on this site that submits data to us.
• We do not have user accounts, profiles, passwords, or logins.
• We do not run a newsletter or mailing list.
• We do not use Google Analytics or any other analytics or tracking product.
• We do not set any cookies of our own.
• We do not build profiles of visitors, and we do not sell, rent, or trade personal information.
• We do not knowingly collect anything from children under 13.

Fonts on this site are self-hosted. They are bundled into the site at build time and served from our own domain, so loading a page does not send a request to Google Fonts or any other font service.

Local Storage on Your Device

The site uses your browser's localStorage to remember two kinds of things:

• History — if the optional History feature is enabled, past calculations are saved so you can look back at them. This is stored only in your browser, on your device.
• Settings — your preferences for units, date format, and light/dark theme.

Local storage is not a cookie. A cookie is attached to every request your browser makes to a server; localStorage is not. Nothing kept in localStorage is transmitted to us, to our host, or to any third party. It sits in your browser's own storage area until you or your browser removes it.

You are in control of it:

• Turn History off in Settings, and nothing further is saved.
• Clear your History and stored settings from the Settings page at any time.
• Clear the site's data through your browser's own settings, which removes everything at once.

Because this data lives on your device, it is visible to anyone who uses that browser profile. If you are on a shared or public computer and would rather not leave a record of your calculations, turn History off or clear it when you are finished.

Server Logs From Our Hosting Provider

The site is served by Firebase Hosting, a Google service. Like effectively every web host, Firebase Hosting automatically records technical information about requests made to the site. This typically includes your IP address, the date and time of the request, the URL requested, your browser's user agent string, the referring page, and the response status.

We want to be straightforward about this: these logs are generated by the hosting infrastructure, not by anything we wrote, and an IP address can be personal data under some laws. We do not use these logs to identify individuals, we do not combine them with anything else, and we do not have any tooling that reads or analyses them for marketing purposes. They exist for delivery, security, and abuse prevention.

Google processes this data as our hosting provider under its own terms. You can read more in the Google Privacy Policy and the Firebase Privacy and Security documentation.

At present the site is also reachable at a Firebase-provided *.web.app address while the production domain is being set up. The same practices described in this policy apply there.

Third-Party Advertising

We intend to display advertisements on One Calculator through Google AdSense. This section describes how that works and applies once ads are running on the site.

Third-party vendors, including Google, use cookies to serve ads based on a user's 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 visit to our sites and/or other sites on the Internet.

Third parties may place and read cookies on your browser, or use web beacons, pixel tags, IP addresses, device identifiers, and similar technologies, to collect information as a result of ad serving on this website. This happens between your browser and the ad vendor directly. We do not receive that information, and we do not have access to those cookies or identifiers.

If we have not opted out of third-party ad serving, the cookies of other third-party vendors or ad networks may also be used to serve ads on this site. Those vendors operate under their own privacy policies. Where we know which additional networks are serving on the site, we will name them here and link to their policies; you may visit those sites to opt out of their use of cookies for personalized advertising, where they offer that option.

For details of how Google uses information from sites that use its services, see How Google uses information from sites or apps that use our services.

Your Advertising Choices

• Opt out of personalized advertising from Google by visiting Google Ads Settings, now presented as My Ad Center.
• Opt out of personalized advertising from many participating vendors at www.aboutads.info (Digital Advertising Alliance).
• If you are in Europe, use Your Online Choices (EDAA).
• You can also block or delete cookies through your browser's own settings. Doing so does not stop ads from appearing; it makes them less relevant.

Opting out of personalized ads does not remove advertising from the site. You will still see ads — they will be non-personalized, chosen from general context such as the page's subject and coarse location rather than from a profile of your browsing.

Consent in the EEA, the UK, and Switzerland

If you are in the European Economic Area, the United Kingdom, or Switzerland, we will present a consent message before personalized advertising cookies or similar identifiers are used, through a consent management platform certified by Google under the IAB Transparency and Consent Framework. Your choice is recorded, and you can change or withdraw it at any time by reopening that consent tool from the link provided in the message or in the site footer.

If you decline consent, you will be served non-personalized or limited ads instead. Some storage that is strictly necessary for the site to work, such as your saved settings, is not covered by that consent request because it never leaves your device.

Legal Bases for Processing (EEA and UK)

If you are in the EEA or the UK, the UK GDPR and the EU GDPR give you specific rights, and we must tell you the legal basis on which any personal data is handled.

• Server logs (IP address, user agent, request details) — legitimate interests, namely delivering the site reliably and protecting it from abuse. Article 6(1)(f).
• Advertising cookies and identifiers — consent, collected through the consent tool described above. Article 6(1)(a). Withdrawing consent is as easy as giving it, and does not affect processing carried out before you withdrew.
• Calculator inputs and local storage — no legal basis is needed, because this data never reaches us or any third party. It is processed on your own device, under your control.

Data controller for the purposes of this policy: the operator of One Calculator. Contact: privacy@onecalculator.app.

Your GDPR Rights

You have the right to access your personal data, to have it corrected or erased, to restrict or object to its processing, to data portability, and to withdraw consent at any time. You also have the right to lodge a complaint with your local data protection authority.

We should be honest about what we can actually act on. Because we hold no accounts and no database, we usually have nothing to look up: there is no record connected to you for us to retrieve, correct, export, or delete. Your calculation history and settings are already fully within your control — clear them from Settings or from your browser at any time.

Where a right relates to data held by Google as our hosting provider or as an advertising vendor, we will pass your request on where we are able to, and we will point you to Google's own tools, which are usually the faster route. For advertising specifically, Google Ads Settings and the consent tool on this site are the direct controls.

Because we are based in India, any data reaching our hosting or advertising providers may be processed outside your country, including in India, the United States, and other locations where Google operates infrastructure. Google's transfer safeguards are described in the Google Privacy Policy.

California Privacy Rights (CCPA/CPRA)

If you are a California resident, the California Consumer Privacy Act, as amended by the CPRA, gives you rights over personal information collected about you.

We do not sell your personal information, and we do not share it for cross-context behavioral advertising in exchange for money. We have never done so.

We should flag one nuance rather than hide it. Under California's broad definitions, allowing third-party advertising cookies on a site can be treated as "sharing" personal information for cross-context behavioral advertising. Once ads are running, third-party ad vendors may set and read identifiers in your browser as described in the advertising section above. You can opt out of that at any time using the links in "Your Advertising Choices". When advertising goes live, we will configure it so that a Global Privacy Control signal from your browser is treated as an opt-out request for that browser.

The categories involved are limited: internet or network activity information such as an IP address, user agent, and pages requested, held in hosting logs, plus advertising identifiers held by ad vendors. We do not collect the categories of sensitive personal information described by the CPRA, and we do not use anything you enter into a calculator for advertising.

You have the right to know what personal information is collected, to request deletion, to request correction, to opt out of sale or sharing, and not to be discriminated against for exercising these rights. We do not offer financial incentives, so there is nothing to discriminate about. To make a request, email privacy@onecalculator.app. As above, in most cases we will have nothing on file to return or delete, and we will tell you so plainly.

Children's Privacy

One Calculator is a general-audience site. It is not directed to children under 13, and we do not knowingly collect personal information from them.

If you believe a child under 13 has provided personal information in connection with this site, contact us at privacy@onecalculator.app and we will look into it. Note that because calculator inputs stay on the device and we hold no accounts, there is generally nothing on our side that could contain a child's information.

Links to Other Sites

Our pages link to outside resources — for example, health authorities such as the WHO and the CDC that we cite as sources, and the opt-out and policy pages named above. Advertisements on the site also lead to third-party destinations.

We do not control those sites, and this policy does not apply to them. When you follow a link away from One Calculator, the privacy policy of the destination governs what happens there. We would encourage you to read it, particularly before entering any personal information.

Security

The site is served over HTTPS with a valid certificate, so traffic between your browser and our host is encrypted. Because we hold no personal data on a server, there is no store of user information here for anyone to breach.

The data that does exist — your History and settings — is on your device, protected by your device and browser. Keeping your browser and operating system up to date is the most useful thing you can do to protect it.

Changes to This Policy

We may update this policy as the site changes: when new calculators are added, when advertising goes live, or when a legal requirement shifts. The current version is always the one on this page, and the effective date at the top tells you when it last changed.

If we make a change that materially affects how information is handled, we will make that clear on the site rather than quietly editing the text. Continuing to use One Calculator after an update means you accept the revised policy.

Governing Law

One Calculator is operated from India, and this policy is governed by the laws of India. The rights described above for visitors in the EEA, the UK, and California are provided because our audience is global, and nothing in this section is intended to limit rights you hold under the laws of your own country.

How to Contact Us

For privacy questions, requests, or complaints: privacy@onecalculator.app

For anything else about the site: contact@onecalculator.app

We read every message and aim to reply within 30 days. If your request concerns data held by Google rather than by us, we will say so and point you to the right place, because that will get you a faster answer than waiting on us.