Rounding Calculator

The default is half up, which rounds a tie of exactly one half away from zero. So 2.5 rounds to 3 and -2.5 rounds to -3. It matches how most people round by hand.

Bankers rounding, also called round half to even, sends a tie to the nearest even integer. So 2.5 rounds to 2 and 3.5 rounds to 4. Spreading ties up and down like this reduces the upward bias you get when you always round halves away from zero.

Ceiling always rounds toward positive infinity, floor always rounds toward negative infinity, and truncation simply drops the extra digits toward zero. For -2.7 they give -2, -3, and -2 respectively, so the sign of the number changes which of the three agree.

Select Nearest multiple and enter the step. The calculator divides the value by that multiple, rounds with your chosen mode, then multiplies back. That is why 47 to the nearest 10 is 50 and works the same for 0.25 or any positive step.

Yes. Each mode respects the sign of the value. Half up sends -2.5 to -3, floor of -2.7 is -3, ceiling of -2.7 is -2, and truncation of -2.7 is -2.

Decimal places must be a whole number, and it can be negative to round to tens, hundreds, and beyond. A non-integer value in that field is rejected with a message. To round to a step like 25 or 0.5, use the Nearest multiple option instead.

Scaling a number by a power of ten can introduce tiny binary noise, such as 1.005 becoming 1.00499999. The engine cleans each intermediate value to 15 significant digits before rounding, which removes that fuzz so ties land where you expect.

The calculator runs entirely in your browser, so the numbers you type are never uploaded. This tool also exposes a JSON API that accepts value, decimalPlaces or nearest, and mode for use in scripts.

Any finite number works, including large or very small values. Text that is not a number, or an infinite value, is rejected with a short error rather than a wrong answer.