Significant Figures Calculator
Count the significant figures in any number and round to a desired precision. This calculator applies scientific convention rules to determine which digits are significant and provides clear explanations.
Significant figures (sig figs) represent the precision of a measurement. They include all digits that are known with certainty plus one estimated digit. Proper use of significant figures ensures that calculations do not imply more precision than the data supports.
Rules for Counting Significant Figures:
- All non-zero digits are significant: 1234 has 4 sig figs.
- Zeros between non-zero digits are significant: 1002 has 4 sig figs.
- Leading zeros are NOT significant: 0.0045 has 2 sig figs.
- Trailing zeros after a decimal point ARE significant: 2.300 has 4 sig figs.
- Trailing zeros in integers without a decimal point are ambiguous: 1500 could have 2, 3, or 4 sig figs. Using scientific notation resolves this: 1.5 x 10^3 (2 sig figs) vs. 1.500 x 10^3 (4 sig figs).
Rounding Rules:
When rounding to n significant figures, look at the (n+1)th significant digit. If it is 5 or greater, round up; otherwise, round down. In multiplication and division, the result should have as many sig figs as the input with the fewest. In addition and subtraction, the result should match the least precise decimal place.