Significant Figures Calculator
Round any number to the correct number of significant figures for chemistry, physics, and engineering. Shows the working and converts to standard form.
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.
Units and Significant Figures
Science calculations require consistent units throughout. Mixed units (some in metres, some in centimetres) are the most common source of errors. Always check: are all values in SI units (metres, kilograms, seconds, kelvin) before substituting into formulas? The number of significant figures in an answer should not exceed the least precise measurement used in the calculation. When quoting a result, scientific notation (e.g. 3.7 x 10 to the power 4) avoids ambiguity about significant figures and
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