Rounding Calculator

Banker's rounding is a method that rounds numbers ending in exactly 0.5 to the nearest even integer. For example, 2.5 rounds down to 2, while 3.5 rounds up to 4. This reduces statistical bias—standard rounding (always rounding 0.5 up) causes rounded datasets to have a slightly higher sum or average than the original values.

To round to significant figures, locate the first non-zero digit on the left side of the number. Count the desired number of digits from that point, then round the last digit based on the digit following it. For example, rounding 0.0456 to 2 significant figures gives 0.046.

Ceiling always rounds a number up towards positive infinity (so 2.1 becomes 3, and -2.9 becomes -2). Floor always rounds a number down towards negative infinity (so 2.9 becomes 2, and -2.1 becomes -3).

In finance, rounding is critical for dealing with fractions of cents in interest or tax rates. In science, rounding to the correct number of significant figures indicates the precision of the measurements, avoiding a false sense of accuracy in calculations.

The rounding digit is the digit at the position you are rounding to (e.g. the tenths place). The decision digit is the digit immediately to the right of it. If the decision digit is 5 or greater, the rounding digit increases by 1 (under standard rules).