Significant Figures Calculator

Significant Figures Rules

What Counts as Significant?

All non-zero digits count. Zeros between non-zero digits count (e.g. 1001 has 4 sig. figs). Leading zeros do NOT count (0.0047 has 2 sig. figs). Trailing zeros in a decimal count (2.50 has 3 sig. figs). Trailing zeros in integers are ambiguous without a decimal point.

Why Significant Figures Matter

Sig. figs communicate measurement precision. A result of 1.234 m implies measurement to ±0.001 m. Writing 1 m implies measurement to ±0.5 m. In science, falsely precise results (reporting more sig. figs than your measurement justifies) are considered a significant error.

Rounding in Calculations

For multiplication and division: the result has the same number of sig. figs as the input with fewest sig. figs. For addition and subtraction: the result has the same number of decimal places as the input with fewest decimal places.