Free online calculators
One place for everyday calculations.
Clear inputs, instant results and the working behind every number. For home projects, money, time and more.
Popular calculators
A good place to start.
Construction & HomeGravel CalculatorWork out how much gravel you need in cubic yards or cubic metres, with an optional weight estimate.OpenConstruction & HomeTile CalculatorHow many tiles and boxes you need for a floor or wall, including grout joints and extra for cuts.OpenConstruction & HomeConcrete Slab CalculatorConcrete volume for a slab or pad in cubic yards or cubic metres, plus the number of premixed bags.OpenConstruction & HomePaint CalculatorWall area and the gallons or litres of paint for a room, minus doors and windows.OpenConstruction & HomeMulch CalculatorHow much mulch your beds need in cubic yards or cubic metres, and how many bags to buy.OpenConstruction & HomeGravel Driveway CalculatorGravel for a driveway built in layers, with the volume and optional weight of each layer.OpenMathPercentage CalculatorPercent of a number, what percent one number is of another, percentage change, and adding or removing a percentage.OpenTime & DateDate CalculatorCount the days, weeks and weekdays between two dates, or add and subtract days, weeks, months and years.Open
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Recently added
- Freelance Rate CalculatorThe hourly and day rate you need to cover your target income, business costs, fees and an optional tax reserve.
- Billable Hours CalculatorHow many hours you need to bill at your rate to reach a target income after expenses, fees and an optional tax reserve.
- Project Pricing CalculatorA fixed project price from estimated hours, your rate, a buffer for overruns, expenses and fees, with an optional deposit.
- Freelance Day Rate CalculatorConvert an hourly rate to a day rate, or a day rate to hourly, and see what it adds up to each week, month and year.
Accuracy first
Numivo adds calculators slowly on purpose. A calculator goes live only when its formula, units and edge cases have been checked.
How we work01
Checked formulas
Every calculation has automated tests against values worked out independently, including edge cases and invalid input.
02
Shows its working
Results come with the steps and formula behind them, so you can see where each number came from.
03
Runs in your browser
No sign-up and nothing to install. Your numbers are calculated on your device and are not sent to us.