All calculators

Ten focused calculators, each with the formula, a worked example and answers to the questions people actually ask.

Showing 10 of 10 calculators

Percentages, increases, discounts and margins in six modes.

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

Monthly payment, total interest and a full amortization schedule.

Exact age in years, months, days — plus your next birthday.

Add or subtract dates, count days between, or count business days.

Split a bill and tip fairly in a couple of taps.

How much rent your income comfortably supports.

The monthly amount that reaches your goal on time.

Net profit, margin, ROI and break-even for real product costs.

Convert between cost, markup, margin and selling price.