Rounding Calculator

How to use

1. 1Type the number you want to round into the input. Decimals, negatives, comma or point separators, and scientific notation like 1.23e4 all work.
2. 2Choose what to round to: Decimal places to keep a set number of digits after the point, or Nearest step to snap to the closest 10, 100, 5, 0.25, or any value you enter.
3. 3Set the precision: pick a decimal-place count or a step, or tap a preset such as 2 dp or Nearest 100.
4. 4Pick a rounding mode. Half away from zero is the standard rule, half to even is banker's rounding, and ceiling, floor, and truncate ignore the half-way point entirely.
5. 5Read the rounded result and the supporting cards, including the two values the number falls between and whether it was an exact tie.
6. 6To round many numbers, open Round a list of numbers, paste one per line, then copy or download the rounded column. Everything stays in your browser.

About this tool

Rounding Calculator rounds a number to a fixed number of decimal places or to the nearest step, and lets you choose exactly how ties are handled. It answers the two questions people actually search for: round to a given number of digits after the decimal point, such as two decimal places for money, and round to the nearest place value or multiple, such as the nearest 10, 100, 1000, 5, 0.5, or 0.25. This is different from rounding to significant figures, which keeps a fixed count of meaningful digits for measurement reporting; here the cutoff is a fixed decimal position or a chosen step, which is what is meant by round to the nearest hundred or round to two decimal places. The mode you pick controls the tie-breaking rule, the single most confusing part of rounding. Half away from zero is the everyday school rule, where a value sitting exactly on the half rounds to the larger magnitude, so 2.5 becomes 3 and -2.5 becomes -3. Half to even, also called banker's rounding, sends ties to the nearest even result, so 2.5 becomes 2 and 3.5 becomes 4, which removes the slight upward bias that always rounding ties up would introduce over many numbers; it is the default in many financial systems and in IEEE 754 floating point. Half toward zero, half to odd, ceiling, floor, and plain truncation toward zero are all available too, so you can match whatever convention a spec, a spreadsheet, or an accounting rule requires. The calculator is careful about the thing that quietly breaks naive rounding tools: binary floating point. Numbers like 1.005 and 2.675 cannot be represented exactly in binary, so the common trick of multiplying by a power of ten, calling the built-in round, and dividing back gives the wrong answer, rounding 1.005 down to 1.00 instead of up to 1.01. This tool rounds the exact decimal string you typed, digit by digit, so the half-way decision is made on the written value rather than on a polluted approximation, and the result is rebuilt as a string so no second error creeps in. It accepts decimals, negative numbers, a comma or a point as the decimal separator, thousands separators, and scientific notation such as 1.23e4. The result panel shows the rounded value, the same value with thousands separators, the original, and the two neighbours the number sits between so you can see why it went the way it did, and a short note tells you whether the value landed exactly on a tie. A batch mode rounds a whole list of numbers at once, one per line, with copy and download, which is handy for cleaning up a column from a spreadsheet. Everything runs in your browser; the numbers you enter are never uploaded, logged, or stored.

Free to use. Works in your browser. No signup, no login.