Free online significant figures calculator. Instantly count significant figures in any number and round to your desired precision. Perfect for chemistry, physics, and engineering students.
A precise tool for counting and rounding significant figures (sig figs). Essential for chemistry labs, physics calculations, and engineering specifications. Understand which digits matter and why.
Significant figures (sig figs) are the digits in a number that carry meaning and contribute to its precision. They include all non-zero digits, zeros between non-zero digits, and trailing zeros after a decimal point.
No. Leading zeros (zeros before the first non-zero digit) are never significant. For example, 0.0045 has only 2 significant figures (4 and 5).
Trailing zeros in whole numbers without a decimal point are ambiguous. The number 1200 could have 2, 3, or 4 significant figures. To avoid ambiguity, use scientific notation: 1.2×10³ (2 sig figs), 1.20×10³ (3 sig figs), or 1.200×10³ (4 sig figs).
Identify the first significant figure, count to the desired number of sig figs, then look at the next digit. If it is 5 or greater, round up the last kept digit. If less than 5, keep the last digit as is.