Free online rounding calculator. Round numbers to nearest integer, decimal places, or significant figures. Supports round up, round down, and standard rounding rules. Instant, private, no ads.
Rounding is the process of approximating a number to a specified precision. This calculator supports multiple rounding modes: standard rounding (half up), always round up (ceiling), always round down (floor), and truncation. You can round to any number of decimal places, or use significant figures for scientific precision. All calculations happen instantly in your browser.
Standard rounding (also called "round half up") means rounding to the nearest value. If the digit after the cutoff point is 5 or greater, you round up. If it's less than 5, you round down. For example, 3.5 rounds to 4, and 3.4 rounds to 3.
Rounding up (ceiling) means always moving to the next higher value, regardless of the trailing digits. For example, ceiling(3.01) = 4, and ceiling(-2.3) = -2. This is useful when you need to ensure you have enough of something.
Rounding down (floor) means always moving to the next lower value. For example, floor(3.99) = 3, and floor(-2.1) = -3. This is useful when you need to limit values to a maximum whole amount.
Significant figures (sig figs) are the digits in a number that carry meaning about its precision. Leading zeros are not significant, but trailing zeros after a decimal point are. For example, 0.00450 has 3 significant figures. This is commonly used in scientific and engineering calculations.
Yes! Negative decimal places round to tens, hundreds, thousands, etc. For example, rounding 1234 to -1 decimal places gives 1230 (nearest ten), and to -2 gives 1200 (nearest hundred).