Rounding Calculator
Round a number to the nearest whole number, ten, hundred, tenth or hundredth, or choose decimal places, significant figures and custom multiples. Compare rounding rules and see why the answer changes with clear step-by-step working.
Round a number online
Choose your rounding precision and rule, then calculate. Exact decimal arithmetic helps preserve halfway cases such as 2.675.
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How to round a number: identify the place you want to keep, examine the next digit, and apply the specified rounding rule. With the common school rule, values below halfway round to the closer lower-magnitude option; values at or above halfway round away from zero. For example, 2.675 rounded to two decimal places is 2.68.
What is a rounding calculator?
A rounding calculator replaces a number with a nearby value at a chosen level of precision. You can round to a whole number, the nearest tenth, hundredth, ten, hundred or thousand, or set how many significant figures should remain.
CalcuPortal also lets you compare the common school rounding rule with banker's rounding, ceiling, floor and truncation. The tool uses the decimal digits you enter rather than relying only on floating-point rounding, which helps handle exact decimal ties.
How to use the rounding calculator
- Enter the positive or negative number you want to round.
- Choose Place value, Decimal places, Significant figures or Nearest multiple.
- Select how precisely to round — for example, 2 decimal places or the nearest 100.
- Choose a rounding rule such as half away from zero, half to even, ceiling, floor or truncate.
- Click Round number to see the result, neighboring values and explanation.
Rounding rules: when should a digit round up?
For the common school rule, look at the first discarded digit. If it is 0–4, leave the retained digit unchanged. If it is 5–9, increase the retained digit by one in magnitude. When the number is negative, a perfect halfway tie such as −2.5 rounds to −3 under the half-away-from-zero convention.
Nearest (half away from zero)
Choose the closest rounded value. An exact halfway value moves away from zero: 2.5 → 3 and −2.5 → −3.
Banker's (half to even)
Round to the nearest value; at an exact tie, choose the even retained digit: 2.5 → 2 and 3.5 → 4.
Ceiling, floor and truncate
Ceiling moves toward positive infinity; floor moves toward negative infinity; truncate moves toward zero. These can give different answers for negative numbers.
Round to the nearest tenth, hundredth and thousandth
The tenths place is the first digit after the decimal point, the hundredths place is the second, and the thousandths place is the third. To round to a chosen decimal place, check the next digit to the right.
| Number | Round to | Result | Why? |
|---|---|---|---|
| 7.46 | Nearest tenth | 7.5 | The hundredths digit is 6. |
| 3.14159 | Nearest hundredth | 3.14 | The thousandths digit is 1. |
| 2.675 | Nearest hundredth | 2.68 | Exact halfway tie; half away from zero. |
| 8.7654 | Nearest thousandth | 8.765 | The fourth decimal digit is 4. |
Round to the nearest whole number, 10, 100 or 1,000
For whole numbers, look at the tenths digit. For the nearest ten, look at the ones digit; for the nearest hundred, check the tens digit. Zeros replace the digits you no longer keep when rounding to a larger place.
| Number | Nearest | Rounded value |
|---|---|---|
| 48.6 | Whole number | 49 |
| 1,256 | Ten | 1,260 |
| 1,256 | Hundred | 1,300 |
| 1,256 | Thousand | 1,000 |
| 3,250 | Hundred | 3,300 |
Rounding to decimal places vs significant figures
Decimal places count digits after the decimal point. Significant figures count meaningful digits starting from the first non-zero digit. For example, rounding 0.004567 to 2 significant figures gives 0.0046, while rounding it to 2 decimal places gives 0.00.
Significant figures are particularly useful when expressing measurement precision. If you need a dedicated guide, use our Significant Figures Calculator.
Why negative numbers round differently
Always rounding upward is not the same as increasing a number's magnitude. For example, ceiling(−2.1) = −2, while floor(−2.1) = −3. Truncation toward zero gives −2. With nearest rounding, −2.5 is an exact tie and the result depends on the selected tie rule.
This is also why programming-language rounding functions may not agree with school examples. Always check the convention expected in a class, spreadsheet, statistical report or financial system.
Nearest multiple and practical rounding
Some values are rounded to a step rather than a power of ten. For example, you may need the nearest ₹0.05, a multiple of 5, or a batch size of 25. Enter the desired positive multiple in the Nearest multiple tab to compare adjacent multiples and obtain the rounded result.
Common rounding mistakes
- Confusing ceiling with school rounding: ceiling always moves toward positive infinity, even for negative numbers.
- Rounding too early: keep adequate precision in intermediate steps before rounding a final answer.
- Mixing decimal places and significant figures: they measure different types of precision.
- Ignoring exact halfway cases: half-away and half-even rules may produce different results.
- Using binary floating-point for decimal ties: values such as 2.675 may not be represented exactly by standard floating-point arithmetic.
- Assuming a rounded number equals the original: rounding introduces a difference that can accumulate in repeated calculations.
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Frequently Asked Questions
How do I round to the nearest tenth?
Keep one decimal digit and look at the hundredths digit. For example, 7.46 rounds to 7.5 using the standard rule.
How do I round to the nearest hundredth?
Keep two decimal digits and inspect the third. For example, 2.675 rounds to 2.68 using the half-away-from-zero rule.
How do I round to the nearest 10 or 100?
To round to 10, check the ones digit. To round to 100, check the tens digit. For example, 1,256 becomes 1,260 or 1,300, respectively.
What is banker's rounding?
Banker's rounding is the half-to-even rule: if the number is exactly halfway between two allowed values, choose the one whose retained digit is even.
What do ceiling, floor and truncation mean?
Ceiling moves toward positive infinity, floor toward negative infinity and truncation toward zero at the selected precision.
Why does −2.5 round to −3?
Under the half-away-from-zero method, exact halfway values increase in magnitude, so −2.5 becomes −3. Different rules may produce a different result.
Can I round to significant figures?
Yes. Choose Significant figures, select 1–12 digits and use the result to express a chosen level of meaningful precision.
Last updated: October 18, 2026. The calculator accepts ordinary decimal notation with up to 30 significant digits and 18 fractional digits. It does not accept fractions or scientific-notation input. Always use the rounding rule required by your school, report or applicable standard.