Significant Figures Calculator
Add, subtract, multiply and divide significant figures. Enter numbers, scientific notation or e notation and select the operator. The calculator does the math and provides the answer rounding to the correct number of significant figures (sig figs).
You can use this calculator to verify your own calculations using significant figures.
Rounding Significant Figures has moved.
Enter whole numbers, real numbers, scientific notation or e notation. Example inputs are, 3500, 35.0056, 3.5 x 10^3 and 3.5e3.
What are Significant Figures?
Significant figures are the digits of a number that are meaningful in terms of accuracy or precision. These digits provide meaningful information about the precision of a calculation or measurement.
Significant Figures Rules
- Non-zero digits are always significant
- Zeros in between non-zero digits are always significant
- Leading zeros are never significant
- Trailing zeros are only significant if the number contains a decimal point
To learn more about rounding significant figures see our Rounding Significant Figures Calculator.
To practice identifying significant figures in numbers see our Significant Figures Counter.
If you are entering a constant or exact value as you might find in a formula, be sure to include the proper number of significant figures.
For example, consider the formula for diameter of a circle, d = 2r, where diameter is twice the length of the radius. If you measure a radius of 2.35, multiply by 2 to find the diameter of the circle: 2 * 2.35 = 4.70
If you use this calculator for the calculation and you enter only "2" for the radius value, the calculator will read the 2 as one significant figure. Your resulting calculation will be rounded from 4.70 to 5, which is clearly not the correct answer to the diameter calculation d=2r.
You can think of constants or exact values as having infinitely many significant figures, or at least as many significant figures as the the least precise number in your calculation. In this example you would want to enter 2.00 for the constant value so that it has the same number of significant figures as the radius entry. The resulting answer would be 4.70 which has 3 significant figures.