About the rounding calculator
Rounding replaces a number with a simpler one that is close to it. Enter a number, choose how many decimal places or significant figures to keep, and pick a rounding method. A table also shows the answer for every method side by side.
The methods differ only in how they treat a tie, a value exactly halfway between two candidates, and in which direction they push other values. Half up sends ties toward positive infinity, half down toward negative infinity, half even to the nearest even digit (used in finance and statistics to avoid bias) and half away from zero sends ties to the larger absolute value, the rule most people learn at school. Truncate always moves toward zero, ceiling always goes up and floor always goes down.
The calculation works on the decimal digits you typed rather than on binary floating-point values, so 1.005 rounded to two places gives 1.01 under half up, as expected.
Formula
- Significant figures: decimal places = figures − 1 − (position of the first non-zero digit)
- Ties: x.5 for whole numbers, x.x5 for one decimal place, and so on
Example
2.5 rounds to 3 with half up and half away from zero, and to 2 with half even. −2.5 rounds to −2 with half up, −3 with half away from zero. 123,456 rounded to 3 significant figures is 123,000.