Fast, free calculators for everyday decisions

Every NumKits tool runs instantly in your browser — no signup, no ads chasing you around, and nothing you type ever leaves your device.

Finance Calculators

Project savings growth with compound interest and optional monthly contributions.

Find your monthly payment, total interest, and yearly amortization schedule.

Turn an annual salary into hourly, daily, weekly, and monthly pay.

Find X% of a number, what percent X is of Y, or the percentage change between two values.

Find your body mass index from weight and height, in metric or imperial units.

Your exact age in years, months, and days from any date of birth.

Count the days between two dates, with weeks and a years/months/days breakdown.

Work out the tip, total, and each person’s share when splitting a bill.

Convert length, weight and temperature units: cm to inches, kg to lbs, °C to °F.

Live word, character, sentence, and paragraph counts with estimated reading time.