Enter Calculation
Scientific notation is supported: 1.20e3, 6.02e23, -0.00500
Example: 12.11 + 18.0 or 25.6 - 3.21
Use ×, *, ÷ or /. Scientific notation is supported.
Significant Figures Calculator
Count significant figures, round numbers, and apply significant-figure rules to addition, subtraction, multiplication and division.
About this calculatorThis calculator follows standard significant-figure rules for common arithmetic operations and supports scientific notation.
What are Significant Figures?
Significant figures are the digits in a number that communicate meaningful measurement precision. They help show how precisely a value is known.
Rules Summary
- For addition and subtraction, round to the least precise decimal place.
- For multiplication and division, round to the fewest significant figures.
- Non-zero digits and interior zeros are significant.
- Leading zeros are not significant.
- Trailing decimal zeros are significant; whole-number trailing zeros can be ambiguous without notation.
Examples
12.3 + 4.56 = 16.9 (3 s.f.)
5.2 × 3.1 = 16 (2 s.f.)
100.0 ÷ 3 = 33.3 (3 s.f.)
0.00450 × 2.0 = 0.0090 (2 s.f.)
Frequently Asked Questions
Significant figures indicate the meaningful precision communicated by a measured or calculated number.
Count non-zero digits and interior zeros as significant, exclude leading zeros, and treat trailing decimal zeros as significant. Trailing zeros in whole numbers can be ambiguous without notation.
Report the result with the same number of significant figures as the input with the fewest significant figures.