Rounding Calculator

Rounding Calculator rounds a number three different ways -- to decimal places, to the nearest ten or hundred or thousand, or to any multiple you choose -- and then shows what every rounding rule would give. Most of the time the rules agree and only one answer exists. The table matters for the case where they do not.

That case is the exact half-way value. 2.5 rounded to a whole number is 3 under the rule taught in school, because half goes away from zero. It is 2 under banker's rounding, which sends half to the nearest even number so that a long column of rounded figures does not drift upwards. It is also 2 under round-half-down. Spreadsheets use the school rule; many statistics packages and accounting systems use banker's.

Rounding to a multiple is the one people reach for least and need most. Prices to the nearest 5p, times to the nearest quarter hour, measurements to the nearest 0.05 -- all of those are a multiple rather than a decimal place, and doing them by hand is where mistakes creep in.

The page shows its working, not just its answer. Where there is a formula it is printed with your own numbers substituted in, so you can check the result rather than take it on trust -- which is the difference between a calculator you can use for something that matters and one you cannot.

Everything runs inside your browser. What you type is never uploaded, never logged and never stored, and the calculator keeps working if your connection drops after the page has loaded.

• Shows rounded, rule used, rounded up, rounded down and difference together, so you are not running it twice
• A results table you can read across
• Updates as you type, with no button to press and no page reload
• Copy the result in one click
• Free, no sign-up, and it runs entirely in your browser

The rounding calculator is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

• Rounding a price to the nearest five or ten pence
• Rounding a measurement to a sensible number of decimal places
• Rounding a population or budget figure to the nearest thousand
• Seeing how banker's rounding differs from the school rule