Rounding reduces a number to a simpler form while keeping it close to the original value.
About this calculator
Rounding reduces a number to a simpler form while keeping it close to the original value. You round to decimal places when money or measurements need fixed precision — for example, ₹1,234.567 rounded to two decimals is ₹1,234.57. Significant figures matter in science: 0.004560 has four significant figures because leading zeros are not counted.
This calculator supports three modes. Decimal places rounds after the decimal point. Significant figures keeps the first N meaningful digits. Nearest unit rounds to the closest 10, 100, or 1000 — useful for estimates like population or sales figures.
Each result shows the rounded value, the original input, and how much changed. For percentage work use the [[percentage]] calculator; for fraction simplification use the [[fraction]] calculator; for error measurement use the [[percentage-error]] calculator.
Common uses
- Round currency and invoice amounts to paise
- Format lab results to required significant figures
- Estimate large totals to the nearest hundred or thousand
- Check homework rounding rules quickly
Frequently asked questions
How do you round 3.14159 to 2 decimal places?
Look at the third decimal (1). Since it is less than 5, keep the second decimal unchanged: 3.14. If the next digit were 5 or higher, you would round the second decimal up.
What are significant figures?
Significant figures are the meaningful digits in a measurement, starting from the first non-zero digit. In 0.004560, there are four significant figures: 4, 5, 6, and the trailing 0.
How do you round to the nearest 100?
Divide by 100, round to the nearest whole number, then multiply by 100. Example: 4,567 → 45.67 → 46 → 4,600.
Does this calculator use standard rounding (half up)?
Yes. When the digit after the cut-off is 5 or greater, the last kept digit increases by one. This matches the usual school and spreadsheet convention.