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Rounding Calculator

Round to decimals, significant figures or any multiple.

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Every rounding mode

The modes only ever disagree on an exact half. Try 2.5 or 3.5 to see where they part company.

ModeResultWhat it does

At every precision

PlacesRoundedSig figsRounded

Rounded

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Details

Original—
Difference—
Rounding error—
Is it an exact half?—

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Banker's rounding — the IEEE 754 and finance default

Round half to even removes the upward bias that always rounding halves up introduces over many values, which is why it is the default in floating-point hardware and in most financial software. Leading zeros never count as significant figures.

Quick Tool Overview

The Rounding Calculator rounds to decimal places, significant figures or any multiple, and shows every rounding mode side by side — half up, half down, half to even, ceiling, floor and truncation — so you can see exactly where they disagree.

What it does
Rounds a number by places, sig figs or a multiple
You give it
A number, a precision type and how much precision
You get back
Every rounding mode compared side by side
Best for
Coursework, reporting figures and understanding tie-breaking
Calculators Free, unlimited use No sign-up Runs in your browser

About the Rounding Calculator

Round a number to a set number of decimal places, to significant figures, or to the nearest multiple of anything you choose. Every rounding mode is calculated at once so you can see where they disagree.

They disagree more often than people expect, and always on the same case: exactly half. Round half up sends 2.5 to 3, round half down sends it to 2, and banker's rounding — round half to even — sends it to 2 but sends 3.5 to 4. That last mode is the default in IEEE 754 floating point and in most financial software, precisely because always rounding halves upward introduces a systematic bias that accumulates over many values. Significant figures are handled properly too, including the leading-zero cases that trip up manual attempts.

Key features of the Rounding Calculator

Six rounding modes

Half up, half down, half to even, ceiling, floor and truncation, all shown at once.

Banker's rounding explained

Why round half to even is the IEEE 754 and financial default: always rounding halves up introduces a systematic bias.

Significant figures done right

Leading zeros are handled correctly, which is where manual attempts usually go wrong.

Round to any multiple

Nearest 5, nearest 10, or fractional multiples like 0.25 for quarter-hour rounding.

Shows the tie cases

The modes only differ on exact halves, and the tool makes that visible instead of hiding it.

How to use the Rounding Calculator

  1. 1

    Enter your number

    Any decimal, negative or very large value.

  2. 2

    Choose the precision

    Decimal places, significant figures, or the nearest multiple.

  3. 3

    Set how much

    How many places or figures, or which multiple to snap to.

  4. 4

    Compare the modes

    Half up, half down, half to even, ceiling, floor and truncation are all shown together.

Frequently asked questions

Round half to even: exact halves go to the nearest even number, so 2.5 becomes 2 and 3.5 becomes 4. It removes the upward bias that always rounding halves up introduces, and is the IEEE 754 default.

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