Free Chemistry tool · Step by step
Significant Figures Calculator
Count significant figures, round any number to n sig figs, and add, subtract, multiply or divide with the correct sig fig rules — each significant digit highlighted. Free for AP, A-level and college labs.
Significant figures
Highlighted digits are significant (4). Non-zero digits, zeros between them and trailing zeros after a decimal point are significant; leading zeros are not.
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FAQ
What are the rules for significant figures?
Non-zero digits are significant; zeros between them are significant; leading zeros are not; trailing zeros count only if there is a decimal point (100. has 3, 100 has 1, 100.0 has 4).
How many sig figs in a multiplication answer?
Multiplication and division keep the fewest significant figures of the numbers used. Addition and subtraction keep the fewest decimal places instead.
Is 1200 two or four significant figures?
Written without a decimal point it is ambiguous and usually counted as 2. Write 1.200 × 10³ (or 1200.) to show four.