Rounding Calculator

This rounding calculator rounds any number to the place value you choose — anywhere from the nearest million down to the nearest ten-thousandth. Type or paste the number, pick the place and the rounding mode, and you get the rounded value together with a one-line explanation of exactly which digit decided the outcome and why.

Unlike most online tools, it never converts your number to a binary float. It rounds the decimal digits you actually typed, so the classic trap cases come out right: 2.675 to the nearest hundredth is 2.68 (a spreadsheet often says 2.67, because the float it stores is fractionally below 2.675), and 1.005 to two decimals is 1.01, not 1.00. If a result ever disagrees with your calculator, the explanation line shows the deciding digit so you can see which one of you is off.

Four modes cover every convention you are likely to meet. Half up is the school standard: a deciding digit of 5 or more rounds away from zero. Half even — banker's rounding — sends perfect ties to the nearest even digit, which cancels out systematic drift in long financial sums. Floor always rounds down toward minus infinity and ceiling always rounds up, matching the floor() and ceil() functions in programming languages.

Use it to check math homework, to round prices and invoice totals to the cent, to trim measurements to a sensible precision, or to simplify big figures to the nearest thousand or million for a report. Everything runs locally in your browser — nothing is sent to a server, and the copy button grabs the rounded result in one click.