Rounding Calculator
Round to decimal places, to the nearest unit, or to significant figures.
Runs in your browser — nothing is sent or saved.
How to use the rounding calculator
- Enter the number to round.
- Choose to round by decimal places, to the nearest unit, or by significant figures.
- Enter the precision.
- Read the rounded value and the rule used.
The three ways to round
Rounding replaces a number with a nearby, simpler one. This rounding calculator can round numbers in the three common styles. Decimal places keeps a set number of digits after the point, so 3.14159 to two decimal places is 3.14. Round to nearest snaps to a chosen step, so 47 to the nearest 10 is 50. Significant figures keeps a set number of meaningful digits, so 0.0043210 to two significant figures is 0.0043.
Significant figures
Significant figures count the meaningful digits, starting from the first non-zero one. They matter in science and engineering, where a measurement should not claim more precision than it has. For 12,345 rounded to three significant figures, you keep 123 and adjust the place value, giving 12,300. The tool handles the place value for you.
How the halfway point is handled
When a digit to drop is exactly 5, this tool rounds half up, meaning the last kept digit goes up. So 2.5 rounds to 3 and 0.125 to two decimal places rounds to 0.13. This is the everyday rule most people learn. Some fields use round-half-to-even instead, so check which convention your work needs.
FAQ
How do I round to a number of decimal places?
Choose decimal places and enter how many you want. The tool keeps that many digits after the decimal point and rounds the rest, so 3.14159 to two places is 3.14.
What does round to the nearest 10 mean?
It snaps the number to the closest multiple of 10. Choose round to nearest and enter 10, and 47 becomes 50, while 42 becomes 40. You can round to any step, including 0.5 or 100.
What are significant figures?
They are the meaningful digits of a number, starting at the first non-zero digit. Rounding to a number of significant figures controls precision without fixing the decimal places.
How does it handle a trailing 5?
It rounds half up, so a dropped 5 rounds the last kept digit upward. That is the common convention taught in school.
Is my information private?
Yes. Everything is calculated in your browser and nothing you enter is uploaded or saved.