Rounding Calculator
Rounding replaces a number with a shorter, simpler one that is close to it. You do it for money, measurements and reports. This calculator rounds to a chosen number of decimal places, to significant figures, or to the nearest ten, hundred or thousand, and shows floor, ceiling and truncation for comparison.
How to use the rounding calculator
- Enter the number you want to round.
- Choose whether to round to decimal places, significant figures or a power of ten.
- Enter how many, then read the rounded value alongside the floor, ceiling and truncated results.
Formula
Look at the digit just after the place you are rounding to. If it is 5 or more, round up; if it is 4 or less, round down. This tool rounds halves away from zero, so 2.5 becomes 3 and −2.5 becomes −3. Significant figures count digits from the first non-zero digit.
Worked examples
Decimal places
3.14159 rounded to 2 decimal places is 3.14, because the next digit is 1.
Significant figures
123,456 to 3 significant figures is 123,000, and 0.004567 to 2 significant figures is 0.0046.
Nearest hundred
1,467 to the nearest 100 is 1,500.
Rounding rules and pitfalls
Which method to use
| Situation | Round to |
|---|---|
| Money | 2 decimal places |
| Measurements | The precision of your instrument |
| Science results | Significant figures of the least precise input |
| Large estimates | Nearest 10, 100 or 1,000 |
Significant figures
Leading zeros never count, trailing zeros after a decimal point do. 0.00450 has three significant figures (4, 5 and 0), while 4,500 is ambiguous without scientific notation: 4.5 × 10³ has two and 4.500 × 10³ has four.
Rounding half up versus banker’s rounding
Everyday rounding sends a five up. Some fields, such as finance software, use “round half to even” to avoid systematic bias: 2.5 rounds to 2 and 3.5 rounds to 4. This tool uses round half up.
Avoid double rounding
Round once, from the original value. Rounding 2.449 to two decimals gives 2.45, and rounding that to one decimal gives 2.5, but rounding 2.449 straight to one decimal gives 2.4. See also the scientific notation converter for very large or small numbers.
Practice problems
Try these yourself first, then check your answer. The answers come from the calculator above.
- Round 7.8449 to 2 decimal places.
Show answer
Rounded to 2 decimal places: 7.84
- Round 58,436 to 2 significant figures.
Show answer
Rounded to 2 significant figures: 58,000
Common mistakes to avoid
- Rounding in the middle of a calculation. Round only the final answer.
- Counting leading zeros as significant figures. In 0.004567 the first significant digit is 4.
- Rounding repeatedly (for example 2.449 → 2.45 → 2.5), which can give a different result from a single rounding to 2.4.
Frequently asked questions
What are the rules for rounding?
Look at the next digit. 5 or more rounds up; 4 or less rounds down.
What is the difference between decimal places and significant figures?
Decimal places count digits after the point. Significant figures count meaningful digits from the first non-zero one.
What is the difference between rounding and truncating?
Truncating just cuts digits off; rounding may increase the last digit.
Why does 1.005 round to 1.01 here?
This calculator rounds the decimal value you typed, avoiding the binary floating-point error that makes some tools give 1.00.
Reviewed September 26, 2026 by the SolveCalcPro editorial team. Found a mistake? Tell us; see our editorial policy.