Significant Figures Calculator

Count significant figures and round to any number of sig figs

Significant Figures
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Rounded Value
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About this Calculator

The Significant Figures Calculator counts how many digits in a number carry real precision and rounds it to a chosen number of significant figures. It follows standard rules: non-zero digits count, zeros between them count, trailing zeros after a decimal point count, and leading zeros never count. Enter decimals or scientific notation (e.g. 3.20e5) and get instant, accurate results.

Privacy Note: All calculations are performed locally in your browser. No data is ever sent to a server or third party.

Significant Figures Calculator FAQ

What are significant figures?
Digits that carry meaningful precision. Non-zero digits count; zeros between them count; trailing zeros after a decimal point count.
Are leading zeros significant?
No. In 0.0045 only the 4 and 5 are significant — two sig figs. Leading zeros only show where the decimal point is.
How does scientific notation help?
In 3.20×10⁵ the coefficient 3.20 shows exactly three significant figures, removing the ambiguity of trailing zeros.