Significant Figures Calculator
Type the number exactly as written (for example 0.00420) — it counts how many significant figures it has, and also shows the rounded form for any target sig figs. Zero rules are important, so the number is taken as text.
Enter values — the result will appear here live.
How to use
- Write the number exactly as it is written — trailing zeros are also counted when there is a decimal point.
- Optional: also enter how many sig figs to round to.
Rules: non-zero digits are always significant; zeros between two significant digits are significant; leading zeros are never significant; in a decimal number, trailing zeros are significant. Scientific notation also works (for example 4.20e3).