Significant Figures Calculator

Count significant figures and round any number to a chosen number of sig figs.

Runs in your browser — nothing is uploaded

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How to use Significant Figures Calculator

Enter your values — the unit for each field is shown next to it.
The result updates instantly as you type.
Copy the results, or change inputs to compare scenarios.

Formula & assumptions

All non-zero digits are significant.
Zeros between non-zero digits are significant.
Leading zeros are never significant.
Trailing zeros are significant only when there is a decimal point.

Example: 0.004050 has 4 significant figures (4, 0, 5, 0).