Rounding Calculator

Rounding replaces a number with a nearby number that is shorter or simpler to read. The rounding mode controls the precision (how many digits to keep) and the direction (toward zero, away from zero, or to the nearest value).

Decimal places counts digits after the decimal point: 3.14159 to 2 decimal places is 3.14. Significant figures counts meaningful digits regardless of where the decimal point sits: 3.14159 to 3 sig figs is 3.14, while 0.00345 to 2 sig figs is 0.0035.

Round up (ceiling) when you cannot have less than the required amount, like ordering paint or buying tickets. Round down (floor) when you cannot have more than is available, like dividing scarce items into shares. Standard rounding is for reporting and reading.

This calculator uses round-half-up away from zero, the rule most often taught in school. 2.5 rounds to 3 and −2.5 rounds to −3. Some scientific contexts use banker's rounding (round-half-to-even) instead; that is not the default here.

Yes. Standard rounds to the nearest value (with half going away from zero). Round up always moves away from zero. Round down always moves toward zero, so −1.7 rounded down is −1, not −2 (that would be 'floor toward negative infinity', a different convention).