Significant figures calculator
Count significant figures in a number and round to a chosen number of sig figs.
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Tool guide
Significant figures calculator: how it works
Practical information to understand the result and use this tool correctly.
About Significant figures calculator
Significant figures track measurement precision, not just decimal places.
Leading zeros never count; trailing zeros depend on the decimal point or scientific notation.
Enter the number exactly as written so the count matches classroom rules.
How to use it
- 1Type the number as written.
- 2Optionally set a target sig-fig count to round.
- 3Read the count and rounded value.
Frequently asked questions
- Is 3400 two or four sig figs?
- Ambiguous without a decimal or scientific notation.
- Leading zeros in 0.0034?
- Not significant — only 3 and 4 count (two sig figs).