About TrueSums

TrueSums is an independent studio project. We build small, free, fast online tools for the money decisions people actually run into — what co-signing a loan does to your debt-to-income ratio, what a medical bill really costs on a deferred-interest plan, whether a short-term rental covers its own costs across the year — and we hold every tool to one rule: show your work.

Most calculator sites give you a number. Ours give you the number, the formula it came from with your values filled in, the sources behind that formula, and the date any changing data was last checked. You shouldn't have to trust us — you should be able to check us. The full standard is on the how we verify page.

The site is intentionally lightweight: no accounts, no paywalls, and every tool runs entirely in your browser — your inputs never leave your device.

Found a mistake, or missing a tool you need? Contact us.