Significant Figures Calculator
Count significant figures and round numbers to a given precision.
What is Sig Figs?
A sig-fig tool for science and engineering: it counts significant digits per the standard rules and rounds values to a requested precision.
How it works
Counting applies the rules (nonzero digits count, captive zeros count, leading zeros don't, trailing zeros count with a decimal). Rounding uses exponential-form digit targeting.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Rounding to sig figs
Round 12,349 to three significant figures (12,300) or 0.004567 to two (0.0046) — with the counted digits highlighted.
Common mistakes
Leading zeros don't count
In 0.00456 only 4, 5, and 6 are significant — the leading zeros just fix the decimal place.
Frequently asked questions
Which digits are significant?
All non-zero digits, zeros between them, and trailing zeros after a decimal point. Leading zeros never count.
Can it also do arithmetic with sig figs?
Yes — results respect the least-precise input, the standard rule for measured-value calculations.