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

1. Non-zero digits are always significant
2. Zeros between non-zero digits are always significant
3. Leading zeros are never significant
4. Trailing zeros are only significant if the number contains a decimal point

Examples of Significant Figures How Many Significant Figures? Which Figures are Significant? 81 2 8, 1 26.2 3 2, 6, 2 0.007 1 7 5200.38 6 5, 2, 0, 0, 3, 8 380.0 4 3, 8, 0, 0 78800 3 7, 8, 8 78800 4 7, 8, 8, 0 78800. 5 7, 8, 8, 0, 0

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.

Rounding Rules

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.

Rounding the Number 305.459 Rounded to How Many sf or dp? Rounded to Significant Figures (sf) Rounded to Decimal Places (dp) 0 -- 305 1 300 305.5 2 310 305.46 3 305. 305.459 4 305.5 305.4590 5 305.46 305.45900 6 305.459 305.459000

To practice identifying significant figures in numbers see our Significant Figures Counter.

For math with significant figures see our Significant Figures Calculator.

References

• Khan, Salman "Significant Figures," The Khan Academy.
• Weisstein, Eric W. "Significant Digits," MathWorld--A Wolfram Web Resource.