Enter any number into the Number field, choose your Round To place value (from billions down to hundred-millionths), and select a Rounding Mode (nearest, half up, half down, ceiling, or floor). Your rounded result appears immediately, along with a breakdown showing the original value versus the rounded value.
Rounded Result
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Original Number
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Difference
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Rounded To
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Rounding a number means replacing it with a simpler approximation that is close in value. For example, rounding 838.274 to the nearest whole number gives 838. Rounding reduces precision to make numbers easier to work with, communicate, or understand.
Identify the place value you want to round to, then look at the digit immediately to its right. If that digit is 5 or greater, round the target digit up by one. If it is 4 or less, keep the target digit as-is and replace all digits to the right with zeros (for whole number places) or drop them (for decimal places).
Choose the decimal place you need — tenths, hundredths, thousandths, etc. — and check the digit one position to the right of it. If that digit is 5 or more, increase the last kept digit by 1; otherwise drop everything after the chosen place. For example, 3.141 rounded to the nearest hundredth is 3.14.
The most common mode is 'round half up', where values exactly halfway between two options round toward positive infinity (e.g. 2.5 → 3). 'Round half down' does the opposite. 'Ceiling' always rounds up toward positive infinity regardless of the fraction, while 'floor' always rounds down. The default 'round to nearest' uses standard half-up behavior.
Under the standard 'round half up' rule, 7.5 rounds up to 8. Under 'round half down', it would round down to 7. The answer depends on the rounding mode you choose — this calculator lets you pick the mode that fits your needs.
It depends on the precision you choose. Rounded to the nearest tenth, 2.47 becomes 2.5 (because the hundredths digit, 7, is ≥ 5). Rounded to the nearest whole number, 2.47 becomes 2 (because the tenths digit, 4, is < 5).
Place value rounding can go in both directions — you can round to the nearest ten, hundred, or thousand (making numbers less precise) or to the nearest tenth, hundredth, or thousandth (keeping more decimal precision). 'Decimal places' specifically refers to how many digits appear after the decimal point.
Rounding makes numbers simpler and easier to communicate without losing meaningful accuracy. It is used in everyday situations like money (rounding to the nearest cent), measurements, statistics, and scientific reporting where excessive decimal places add clutter but no practical value.