Significant figures are the digits that carry meaning regarding the precision of a measurement. They include all non-zero digits, sandwiched zeros, trailing zeros after a decimal point and, in some cases, leading zeros after the decimal.
Significant Figures Calculator
Count significant figures and identify each digit with applied rules.
Precise significant-figure identification with detailed rules.
Significant figures indicate the precision of a measurement. The main rules are: (1) non-zero digits are always significant; (2) zeros between non-zero digits are significant; (3) trailing zeros with a decimal point are significant; (4) leading zeros are not significant; (5) trailing zeros in integers without a decimal point are ambiguous.
Enter a number and see each digit classified.
- Enter the number (integer, decimal or scientific notation).
- The tool counts significant figures and colors each digit.
- Read the applied rules to understand the result.
Sources and references for this tool
These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
- Significant Figures — NIST Guide to SINIST — NIST measurement uncertainty guide and significant figures.
- Significant Figures — WikipediaWikipedia — Rules and conventions for significant figures in science.
- Significant Figures — Khan AcademyKhan Academy — Significant figures rules review with exercises.