About CalcKit

CalcKit is a collection of 30 free online calculators covering health (BMI, body fat, BMR, water intake, sleep, calories, pregnancy due date), finance (EMI, mortgage, rent vs buy, refinance, debt payoff, retirement, compound interest, salary tax, currency), productivity (word counter, GPA, password generator, QR codes, time zone planner, Pomodoro timer), freelance work (invoice generator, hourly rate) and everyday maths (age, tip, percentage, scientific, unit conversion, date difference).

Private by design

Every calculation runs locally in your browser using JavaScript. We don't ask for accounts, and your inputs are never sent to our servers. Your recent calculations are stored only in your own browser's local storage, which you can clear at any time.

Free forever

All calculators are free to use without limits. The site is supported by advertising, which is why you may see ad placements on some pages.

Accuracy

We use standard, widely accepted formulas (for example, the Mifflin-St Jeor equation for calories and the standard reducing-balance formula for loans). Results are estimates for planning and education — see our Disclaimer.