Frequently asked questions

Yes. Every tool on Reeliy is free to use, with no sign-up, no trial period and no paywall. The site is funded by advertising; see the Advertising Disclosure.

No. There are no accounts, logins or forms to fill in. Open a tool, type your numbers and read the result.

The calculation runs in your browser, and the site never uploads what you type: no form sends your input to us. There is one thing to know: once you press the button (or "Reload page" when a page could not finish loading), what you typed is added to the page address so that the result can be reloaded or shared. That covers numbers, text you enter in a text tool (a list of names, a string to hash) and, on the search page, the phrase you search for. An address is not private. Anyone you send it to can read it, and your browser sends it to our hosting provider, which logs it, whenever you reload the page or open a link that holds it, and the requests for ads can include it too. Google Analytics is set up to receive the page address without the numbers. Pages of this site pass on only the site's own name, not the full address, as the referrer. So do not type passwords or other secrets into a tool, and when you share a tool use "Copy link" rather than "Copy link with my values" unless you are happy for the other person to see your values. See the Privacy Policy and the Cookie Policy for the details.

Each tool is built from standard, published formulas and checked against worked examples, against the standard formula or a published reference where one exists, and against other calculators. Where another calculator disagrees with the formula, we follow the formula. The tools have not been audited by an outside specialist, and results are still estimates for general information: inputs, rounding and assumptions all matter. Read the Editorial Policy for how we build and test tools, and the Disclaimer before relying on a result for an important decision.

Different tools often round at different steps, assume different conventions (for example how a month or a year is counted) or use slightly different constants. Each of our guides states the formula and assumptions it uses, so you can see exactly where a difference comes from.

Yes. After you press the button, the page address changes to include your inputs, so you can bookmark it or copy it from your browser. To share the calculation, open "Share" under the form and choose "Copy link with my values" (it appears once a result is showing); anyone who opens that link sees the same calculation, and can read your numbers. The other Share items, "Facebook", "X", "LinkedIn", "Email" and "Copy link", send only the tool's own address, without your numbers, so use "Copy link" when you do not want to share your values. On a device where "Share" opens the device's own share sheet, that sheet also shares only the tool's address; to send your values from there, copy the address from your browser's address bar.

Yes, free of charge. Every tool has an embed code, under "Embed" in the row of buttons under the form, and the widgets page lets you pick any tool and copy its code. Use the code as it is given and keep the link back to the original tool page that the widget shows; the conditions are in the Terms of Use. A widget sets no cookies, loads no analytics or ads and has no share buttons.

Please email support@reeliy.com with the name of the tool, the values you entered, the result you expected and the result you saw. We check every report, fix confirmed errors promptly and update the page's "Last updated" date. See the contact page for what to include.

Probably. Send the idea to support@reeliy.com and describe what you want to work out, with an example if you have one. We cannot promise every request, but suggestions are how the catalog grows.

No. They are general-purpose calculators. For decisions about your health, money, taxes or legal position, speak to a qualified professional. The Disclaimer has the details.

Use the "Privacy and cookie settings" link in the footer of any page; "Do Not Sell or Share My Personal Information" opens the same dialog. It reopens and your new choice applies immediately: "Essential only" switches off analytics and advertising storage, "Accept all" allows it. Closing it with the Escape key saves no choice, so the default for your region stays in force. If your browser sends a Global Privacy Control signal and you have not chosen yourself, we treat it as "Essential only". See the Cookie Policy.

In your own browser only, never on our servers. Un-star a tool to remove it, use Clear recent to empty the list of the last tools you opened (it fills again as you open tools), or clear the site data in your browser settings.

You may quote short passages with a link back to the page. Copying whole guides or tools, or republishing them elsewhere, needs permission; the one exception is the embed code on the widgets page. See the Terms of Use. A ready-made citation is at the bottom of every tool page.

Yes. The pages are built mobile-first, load quickly on slow connections, and every tool can be used with a touch screen or a keyboard.