About the Rounding & Significant Figures Calculator
Round positive or negative values using a chosen precision and rounding rule. Compare ordinary rounding, bankers' rounding, floor, ceiling and truncation.
Formula or method
Decimal-place rounding scales a value by a power of ten before rounding. Significant-figure rounding chooses precision based on the magnitude of the original number. Rounding to a multiple rounds the quotient value ÷ step, then multiplies the result by the step.
Worked example
Round 1234.5678 to two decimal places to obtain 1234.57. Round 1234.5678 to four significant figures to obtain 1235. Round 47 to the nearest multiple of 5 to obtain 45.
How to use the tool
Start with the example values above, then replace each input with your own figures. The results update immediately. Review the units, denominators, and assumptions before using any number in an important decision.
Assumptions and limitations
The tool uses JavaScript binary floating-point numbers, so results near exact decimal ties can be affected by representation. Supported decimal places are −12 through 12; significant figures 1 through 15. It is not intended to implement legal or financial rounding rules for every jurisdiction.
Frequently asked questions
What is the difference between half-to-even and half-away-from-zero?
At an exact tie, half-away rounds magnitude upward, so 2.5 becomes 3 and −2.5 becomes −3. Half-to-even chooses the even neighboring integer, so 2.5 becomes 2 and 3.5 becomes 4.
Privacy and support
Your inputs are processed locally in your browser. ToolMosaic does not upload or store the values you enter in this tool. Our tools are free, and we appreciate your support.