Less guesswork.
More clarity.
From the everyday to the wonderfully specific. Simple calculators, useful converters, and the formulas behind them.
Everyday essentials
A good place to start, whatever you’re working on.
Percentage calculator
Find a percentage of any number. Calculate discounts, portions and everyday percentages with precise decimal arithmetic.
Open toolCompound interest calculator
See how a starting balance grows with compound interest. Compare rates, time horizons and compounding frequencies.
Open toolConcrete calculator
Estimate concrete volume for a rectangular slab and include an allowance for waste. Enter all dimensions in metres.
Open toolLength converter
Convert metric and imperial distances, including metres, feet, inches and miles.
Open toolLoan payment calculator
Estimate a fixed monthly loan payment, total interest and total repayment from a loan amount, annual rate and term.
Open toolCircle area calculator
Find the area and circumference of a circle from its radius. Use any consistent length unit.
Open toolDate difference calculator
Count the calendar days between two dates, with leap years handled automatically and no timezone shift.
Open toolFactorial calculator
Calculate exact factorials from 0 to 1,000, including integers much larger than ordinary floating-point numbers can represent.
Open toolFind your field
Small questions. Big projects. There’s a tool for that.
New to the toolkit
More ways to make everyday numbers make sense.