Significant Figures Calculator
Significant figures calculator: count the sig figs in a number and round it to any number of significant figures, with scientific notation.
0.00450 → 3
How to use this calculator
- Type your input in the box.
- The result updates as you type.
- Use “Copy result” or “Copy link” to share it.
Significant figures are the digits that carry meaning about a measurement’s precision. All non-zero digits count; zeros between them count; leading zeros never count; trailing zeros count only if there is a decimal point.
Type the number exactly as written, since 1200 and 1200. have different significant figures. The calculator rounds to the precision you choose and gives the scientific notation.
Worked example
0.004500 has 4 significant figures (the leading zeros do not count, the trailing ones do). Rounded to 2 it becomes 0.0045 = 4.5 × 10⁻³.
Frequently asked questions
How many significant figures does 1200 have?
Two, by convention, because the trailing zeros may only be placeholders. Write 1200. or 1.200 × 10³ to show four.
How many significant figures should a result have?
For multiplication and division, as many as the input with the fewest. For addition and subtraction, round to the fewest decimal places.