Significant Figures Calculator
Count significant figures and round a number to your chosen precision.
How Significant Figures Work
Significant figures describe the precision carried by a measured or reported number. They help prevent a calculation from implying more accuracy than the original data supports.
Rules
Non-zero digits are significant, zeros between non-zero digits are significant, leading zeros are not significant, and trailing zeros after a decimal point can be significant.
Worked Example
The value 0.004560 has four significant figures: 4, 5, 6 and the final zero. Rounded to three significant figures, it becomes 0.00456.
Factors That Affect the Result
Decimal placement and written trailing zeros can change how many significant figures a value communicates. Scientific notation is often the clearest way to show intended precision.
Frequently Asked Questions
Are leading zeros significant?
No. Zeros before the first non-zero digit only locate the decimal point.
Are trailing zeros always significant?
No. Their meaning depends on how the number is written; decimal notation or scientific notation can make the intended precision clear.
Why use significant figures?
They keep reported results consistent with the precision of the measurements used in a calculation.
Significant Figures and Measurement Precision
Significant figures communicate the precision justified by a measured or reported value. Leading zeros are generally not significant, while zeros between nonzero digits are. Trailing zeros can depend on notation, so scientific notation is useful when precision would otherwise be ambiguous. Round at the end of a calculation to avoid unnecessary accumulated error.
Calculation Details and Edge Cases
Significant figures communicate measurement precision. Leading zeros are not significant, zeros between nonzero digits generally are, and trailing zeros can be ambiguous without decimal notation or scientific notation; round only after completing intermediate calculations when possible.