Number Rounding Calculator
Round numbers instantly to the nearest whole, decimal place, significant figure, or multiple (e.g., nearest 5, 10, 0.5). Perfect for math, science, and finance.
Rounding Parameters
Enter number and select rounding method
Enter any positive or negative decimal number
Number of decimal places (e.g., 2 for 0.01)
Rounded Result
Calculated value and analysis
Enter a number and select a rounding method, then click Round Number to see the result.
Rounding Examples
How the number 3.14159 is rounded using different methods.
| Rounding Method | Result | Explanation |
|---|---|---|
| Nearest Whole | 3 | Decimal part .14… is less than .5, so round down. |
| 2 Decimal Places | 3.14 | Third decimal is 1 (<5), so keep second decimal as 4. |
| 4 Decimal Places | 3.1416 | Fifth decimal is 9 (≥5), so round fourth decimal up to 6. |
| 3 Significant Figures | 3.14 | First 3 digits are 3, 1, 4. Next digit is 1 (<5). |
| Nearest 0.5 | 3.0 | 3.14159 is closer to 3.0 than to 3.5. |
| Nearest 10 | 0 | 3.14… is closer to 0 than to 10. |
Rounding Rules FAQ
Everything you need to know about rounding numbers correctly.
The standard rule (Round Half Up) is: identify the digit to the right of the place you are rounding to. If it is 5 or greater, round up (increase the target digit by 1). If it is 4 or less, round down (keep the target digit the same). All digits to the right are then replaced with zeros or dropped.
Significant figures (sig figs) are the digits in a number that contribute to its measurement resolution. This includes all digits except leading zeros, trailing zeros when they are merely placeholders, and spurious digits introduced by calculations. For example, 0.0052 has two significant figures (5 and 2).
To round to the nearest multiple (like 5, 10, or 0.5), divide the number by that multiple, round the result to the nearest whole number using standard rules, and then multiply back by the multiple. For example, to round 23 to the nearest 5: 23 / 5 = 4.6 → rounds to 5 → 5 * 5 = 25.
Also known as Banker’s Rounding, this method rounds half-way values (ending in .5) to the nearest even number. For example, 2.5 rounds to 2, and 3.5 rounds to 4. This minimizes bias in large datasets and is the default rounding mode in IEEE 754 floating-point arithmetic.
Rounding negative numbers follows the same logic as positive numbers regarding magnitude. ‘Rounding up’ usually means moving towards positive infinity (e.g., -2.6 rounds to -2), while ’rounding down’ or ’rounding half away from zero’ moves away from zero (e.g., -2.6 rounds to -3). This calculator uses Round Half Away From Zero as the standard method.