Significant Figures Calculator
Enter a number to see how many significant figures it has. Choose a count to round it to that many significant figures.
Result
- Rounded value in scientific notation
- 4.6 × 10⁻³
- Your number in scientific notation
- 4.560 × 10⁻³
Trailing zeros in a whole number written without a decimal point, such as 1500, are treated as not significant. Write 1500. or 1.500 × 10³ to show that they are.
Formula
- Non-zero digits are always significant
- Zeros between non-zero digits are significant
- Leading zeros are never significant
- Trailing zeros are significant only when the number has a decimal point
How the Significant Figures Calculator works
Significant figures are the digits of a measurement that carry real information about its precision. A length written as 4.50 m claims more precision than 4.5 m, even though the two are numerically equal.
When multiplying or dividing measurements, the answer should have as many significant figures as the least precise input. When adding or subtracting, it should have as many decimal places as the least precise input.
Worked example
0.004560 has four significant figures: 4, 5, 6 and the trailing zero. The leading zeros only place the decimal point. Rounded to two significant figures it is 0.0046, or 4.6 × 10⁻³.
Frequently asked questions
How many significant figures are in 100?
One, unless a decimal point is shown. Written as 100. it has three, and as 1.0 × 10² it has two.
Are zeros after a decimal point significant?
Trailing zeros after a decimal point are significant: 2.50 has three. Leading zeros are not: 0.025 has two.
How many significant figures does 0.00340 have?
Three: the 3, the 4 and the final zero.
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Calculations run in your browser and nothing you enter is sent to a server. Results are provided for general information. Check critical figures independently before relying on them.