Contact

Email is the way to reach One Calculator. We read everything that arrives — bug reports, corrections, calculator suggestions, privacy questions and plain feedback all land in a real inbox, and a person answers them.

Where to write

contact@onecalculator.app — general enquiries. Use this for feedback on a calculator, a result you think is wrong, a suggestion for a calculator we should build next, a broken link or layout problem, accessibility issues, or anything about the site that does not fit elsewhere.

privacy@onecalculator.app — privacy and data questions. Use this for anything about our Privacy Policy, about advertising and third-party cookies, or about your rights under the GDPR (EEA and UK) or the CCPA/CPRA (California). Because the site has no accounts and no server, we hold no personal data about visitors to look up — but if you want that confirmed in writing, or want to understand exactly what a third-party ad network may be doing in your browser, write here and we will answer specifically.

Either address reaches us. If you pick the wrong one, we will simply route it internally rather than send you away.

Reporting a calculation error

A wrong number is the report we take most seriously, and the one we most want to get right. The single thing that determines how fast we can fix it is whether we can reproduce it. Please include:

• Which calculator — Age or BMI — and, for the Age Calculator, whether you were in "Your age" mode or "Age difference" mode.
• The exact inputs you entered. For age: the date of birth (write it out, e.g. 29 February 2004, so there is no DD/MM versus MM/DD confusion), the time of birth if you set one, and the "calculate age on" date if you changed it from today. For BMI: height and weight with their units exactly as you typed them (5 ft 9 in, or 175 cm; 68 kg, 150 lb or 10.7 st), plus the waist measurement if you used one.
• The result you got — the actual numbers on screen, copied or typed out.
• The result you expected, and briefly why. Even "my other calculator says 34 years 2 months" helps us see which of us is handling the month boundary differently.
• Your settings, if you changed any — date format, units, or whether History was on.
• Your device and browser — for example "iPhone, Safari" or "Windows 11, Chrome". Some bugs only appear in one browser's date handling.
• A screenshot, if it is easy. Not required, but it removes most ambiguity in one step.

A useful report looks like this: *"Age Calculator, date of birth 29 February 2004, calculated on 1 March 2026. It shows 22 years 0 months 0 days; I expected 22 years 0 months 1 day. Chrome on Windows, date format DD/MM/YYYY."* That takes a minute to write and lets us reproduce the case immediately.

If you would rather not share your own real date of birth or measurements, that is completely fine — construct an example that produces the same wrong behaviour and send that instead. We do not need your actual data to fix our maths.

When to expect a reply

We usually respond within a few business days. One Calculator is run by a small independent operation based in India (IST, UTC+5:30), so a message sent over a weekend or an Indian public holiday will most likely be answered the following week.

There is no auto-reply, so you will not get an instant confirmation — that does not mean the message went missing. If a week goes by with no answer, do send a follow-up; occasionally something is caught by a spam filter on one side or the other.

Privacy requests are prioritised and answered inside the timelines the applicable law requires, as described in our Privacy Policy.

What we cannot help with

Medical advice. We cannot interpret your BMI, tell you what you should weigh, or advise on diet, exercise, medication or any health condition. BMI is a screening measure, not a diagnosis — it cannot distinguish muscle from fat, and it is read differently for children, teenagers, pregnant people and older adults. Please talk to a doctor, dietitian or other qualified healthcare professional about what your number means for you.

Legal advice. We cannot tell you whether a calculated age satisfies a legal age requirement, an eligibility cut-off, a visa rule, a school admission date or a contract deadline. Those rules vary by jurisdiction and often define age in ways our general-purpose calculator does not model. Consult a qualified lawyer or the relevant authority.

Financial advice. We cannot advise on loans, investments, insurance, tax or any other financial decision.

We will happily explain how one of our calculators arrived at its number, and fix it if it is wrong. We cannot tell you what to do about the number. This is set out in full in our Terms of Service.

Why there is no contact form

One Calculator is a fully static site. There is no server, no backend and no database behind it — which is precisely why nothing you type into a calculator can be transmitted anywhere. A contact form would need a server to receive the submission, so we do not have one. Email does the same job without asking you to trust an intermediary.

The trade-off is worth naming: when you email us, your address and whatever you write are handled by our email provider in the ordinary way, and we keep the message so we can follow up on the issue. We use it only to reply to you and to fix what you reported. We do not add you to any mailing list — we do not operate one — and we do not pass your address to anyone else. Please do not send passwords, financial details, government ID numbers or health records; we never need them, and a bug report never requires them.

Business and other enquiries

Advertising, partnership, press and any other business matter: contact@onecalculator.app. Please put the topic in the subject line so it does not sit behind the support queue.

For legal or formal notices, write to contact@onecalculator.app with "Legal notice" in the subject line. One Calculator is operated from India, and these services are governed by Indian law, as set out in our Terms of Service.