Significant Figures Calculator — Round to Sig Figs

Significant figures (sig figs) are the digits in a number that carry meaningful information. They include all non-zero digits, zeros between non-zero digits, trailing zeros in a decimal, and leading zeros do NOT count. For example, 0.00470 has 3 sig figs.

Captive zeros (between non-zeros) are always significant (e.g., 1005 — 4 sig figs). Trailing zeros with a decimal point are significant (e.g., 10.0 — 3 sig figs). Leading zeros are never significant (e.g., 0.0025 — 2 sig figs). Trailing zeros without a decimal are ambiguous.

Find the nth significant figure. Look at the next digit: if it is 5 or more, round up; if less than 5, round down. Replace remaining digits with zeros (or remove them for decimals). Example: 45,678 to 3 sig figs = 45,700.

Significant figures indicate the precision of a measurement. Using too many sig figs implies false precision, while too few loses information. In scientific calculations, results should not have more sig figs than the least precise measurement used.

Accuracy is how close a measurement is to the true value. Precision (related to sig figs) is how reproducible and specific a measurement is. A reading of 3.14159 is more precise than 3.1, regardless of the true value.