Significant Figures Calculator

Counting significant figures and rounding to a chosen precision are routine steps in science, engineering, and quantitative reporting, and this tool does both for any number you enter. Precision carries real weight: when a figure gets reported, the number of significant figures signals how much confidence the value actually warrants, and getting it wrong can overstate or understate the certainty behind it.

Counting follows the standard conventions. Every non-zero digit counts, as does any zero sitting between non-zero digits. Leading zeros that come before the first non-zero digit never count, while trailing zeros count only when the number includes a decimal point. Rounding looks at the digit just past the last figure you want to keep: a 5 or higher rounds that figure up, anything lower leaves it alone, and the digits beyond become zeros if they fall before a decimal point or simply disappear if they fall after one.

People often blur significant figures with decimal places, but the two count entirely different things. Context shapes meaning as well, since '2.00 meters' claims a finer measurement than '2 meters' even though both describe the same length. In multi-step work, hold off on rounding until the end, because trimming intermediate values too soon lets small errors stack up and skew the final answer.