About NumKits

NumKits is a collection of free online calculators and converters built around one simple idea: when you need to know a loan payment, a percentage, or how many days are left until a deadline, you shouldn't have to create an account, close three pop-ups, or wait for a bloated page to load. You should type a couple of numbers and get the answer.

How our tools work

Every tool on this site runs entirely in your browser. There is no server crunching your numbers and no database storing what you type — your salary, your loan amount, your weight, your dates never leave your device. That's not a marketing claim; it's how the site is built. The pages are static files, and the math happens in a few kilobytes of JavaScript on your own computer.

How we verify accuracy

Each calculator is built from the standard published formula for its domain — for example, the amortization formula used by lenders for loan payments, or the WHO thresholds for BMI categories. Every tool is tested against known reference answers before it ships, and the formula behind each tool is explained openly on its page so you can check the work yourself. If you ever spot a discrepancy, we want to know — reach out via the contact page.

A note on advice

Our tools are for information and planning. They're great for quick estimates and sanity checks, but they aren't a substitute for a financial advisor, a doctor, or an accountant who knows your situation. Big decision? Use the calculator to get oriented, then talk to a professional.

What's next

NumKits grows steadily — we add new calculators based on what visitors ask for. If there's a tool you wish existed, tell us and there's a good chance it will show up here.