Calculators

About these calculators

Five calculators for questions that come up often enough to be worth a dedicated page. Each one shows its working rather than just an answer, because a number without its assumptions is hard to trust. The finance and security calculators carry a last-updated date and an explicit note on their limits — an estimate produced from a handful of inputs is a starting point for a conversation with a professional, not a substitute for one.

Every tool has its own page, its own explanation and its own worked example, so you can bookmark the one you use most instead of hunting through a tab bar. They all work offline once the page has loaded, they all work on a phone, and none of them ask you to create an account or wait in a queue.