Significant Figures Calculator
Round any number to a specified number of significant figures, identify all sig figs, and see full rounding working.
What are Significant Figures?
Significant figures (sig figs) are the meaningful digits in a number that contribute to its precision. Rules: all non-zero digits are significant; zeros between non-zero digits are significant; leading zeros are NOT significant; trailing zeros after a decimal point ARE significant.
How to Count Significant Figures
In 0.00456: the leading zeros are not significant, so there are 3 sig figs (4, 5, 6). In 12300: ambiguous without a decimal point — could be 3, 4, or 5 sig figs. In 12300.: the decimal point indicates 5 sig figs.
Frequently Asked Questions
How many significant figures does 0.00205 have?
3 sig figs: 2, 0, and 5. The leading zeros before 2 are not significant. The zero between 2 and 5 is significant because it sits between two non-zero digits.
How do you round 12345 to 3 significant figures?
12300. Keep the first 3 significant digits (1, 2, 3) and replace the remaining digits with zeros.
Why are significant figures important?
They communicate the precision of a measurement. Too many figures implies false precision. In science, using the correct sig figs ensures results honestly represent the accuracy of the original measurements.