Rounding Significant Figures Calculator
Round a number to a quantity of significant figures that you provide.
Enter whole numbers, real numbers, scientific notation or e notation. Example inputs are, 3500, 35.0056, 3.5 x 10^3 and 3.5e3.
Rounding Significant Figures Rules
- Non-zero digits are always significant
- Zeros between non-zero digits are always significant
- Leading zeros are never significant
- Trailing zeros are only significant if the number contains a decimal point
In rounding significant figures, when an integer contains more digits than are significant, the last significant digit has an overline to indicate that it is the last significant digit.
When rounding significant figures the standard rules of rounding numbers apply, except that non-significant digits to the left of the decimal are replaced with zeros.
Example: 356 rounded to 2 significant digits is 360
This calculator rounds down if the next digit is less than 5 and rounds up when the next digit is greater than or equal to 5.
In the table below 305.459 is rounded from 0 to 6 significant figures. For comparison the same number is rounded from 0 to 6 decimal places. You can see the difference between rounding for significant figures and rounding to decimal places.
sf or dp?
Significant Figures (sf)
Decimal Places (dp)
To practice identifying significant figures in numbers see our Significant Figures Counter.
For math with significant figures see our Significant Figures Calculator.