Significant Figures Calculator (Chemistry)

Significant Figures Calculator (Chemistry). In chemistry and science, significant figures are the meaningful digits in a measurement that reflect its precision — and knowing how to count or round them correctly is fundamental to any calculation. Enter a number or expression (such as 5.452 × 1.67) into the Significant Figures Calculator and select whether to count sig figs or round to a specific number of them. You'll get the significant figures count, the rounded result, and the value expressed in scientific notation. Also try the calculate Mass Spectrometry Theoretical m/z.

Enter Number or Expression *

Enter a number or simple expression (supports +, -, ×, ÷)

Operation Type *

Round to Sig Figs

Results

Significant Figures

Original Number

Rounded Result

Scientific Notation

Results Table

What are significant figures?

Significant figures are the meaningful digits in a number that indicate the precision of a measurement or calculation. They include all non-zero digits, zeros between non-zero digits, and trailing zeros in decimal numbers. See also our Standard Deviation Calculator (Chemistry).

How many significant figures are in 0.0098?

The number 0.0098 has 2 significant figures. The leading zeros (0.00) are not significant as they only indicate the decimal place, while the digits 9 and 8 are significant.

Does 5000 have 1 or 4 significant figures?

The number 5000 is ambiguous - it could have 1, 2, 3, or 4 significant figures depending on how it was measured. To clarify, write it in scientific notation: 5×10³ (1 sig fig) or 5.000×10³ (4 sig figs).

How do you round to a specific number of significant figures?

To round to n significant figures: count n digits from the first non-zero digit, then round the last digit based on the following digit. If it's 5 or greater, round up; if less than 5, round down.

What are the rules for significant figures in multiplication and division?

In multiplication and division, the result should have the same number of significant figures as the measurement with the fewest significant figures. For example: 5.45 × 2.1 = 11 (2 sig figs).

How many significant figures in 100.00?

The number 100.00 has 5 significant figures. The decimal point indicates that all trailing zeros are significant, making all five digits (1, 0, 0, 0, 0) meaningful.

Are zeros always significant figures?

No, zeros are significant only in certain cases: zeros between non-zero digits are always significant, trailing zeros after a decimal point are significant, but leading zeros are never significant.

How do significant figures apply to scientific notation?

In scientific notation (like 3.45×10⁵), only the digits in the coefficient (3.45) count as significant figures. The exponent doesn't affect the count, so this number has 3 significant figures. You might also find our calculate Native Mass Spectrometry useful.