Significant figures, or sig figs, tell the reader how precise a measurement really is. In science and engineering, writing every digit a calculator spits out can overstate how well you actually measured something. This tool counts the significant figures in any number and rounds it to the precision you choose.
It also converts your number into scientific notation, the cleanest way to make precision unambiguous — a number like 0.004520 written as 4.520 × 10⁻³ clearly carries four significant figures.
Are trailing zeros significant? Only when a decimal point is present. In 100 the zeros are ambiguous, but in 100.0 they are significant.
Why use scientific notation? It removes ambiguity about trailing zeros and shows the exact number of significant figures.
Is my data private? Yes, all calculations happen locally in your browser.