Significant Figures: Counting What Actually Counts
Significant figures record measurement precision, and zeros are the tricky part. This counter applies the standard rules to the number as typed.
What is the Significant Figures Counter?
Enter a number as text, including any decimal point and zeros. The tool applies the standard counting rules: leading zeros do not count, trailing zeros after a decimal do, and zeros between digits do. It counts digits in the string you type, not in a rounded value.
How to use it
- Enter the number as text, exactly as written.
- Click Count Significant Figures.
- Read the count and the rule used.
Worked example
0.00450 has 3 significant figures: the digits 4, 5, and the trailing 0 after the decimal point, while the leading zeros do not count.
How many significant figures does 0.00450 have?
Three: 4, 5, and the trailing zero, since leading zeros never count.
Frequently asked questions
Why do trailing zeros count after a decimal?
Because writing them claims that precision was measured, not guessed.
Does 1200 have 2 or 4 significant figures?
Without a decimal point it is ambiguous; this tool counts 2, treating trailing zeros as placeholders.