About

SumCrane is a small set of everyday calculators that run in your browser: percentages, dates and ages, compound interest, units, BMI and a few others.

The numbers you type are processed on your own device and are not sent to a server. A calculator does not need one, and a page that never receives your figures cannot leak them.

The site is paid for by advertising. There are no accounts, no subscriptions and no paid tier, and no tool is deliberately limited to sell you a better version of itself. Where a tool does have a limit, it is a technical one and the page says so plainly.

Behind it is one independent developer rather than a company with a support desk, which is worth knowing before you write in. The formal publisher details are on the legal notice page, and questions, bug reports and requests for a missing tool are welcome at contact@sumcrane.com.