Significant Figures

Significant Figures Calculator is an educational website designed to help students and anyone working with measurements understand and apply significant-figure rules. Its free calculator can count the significant figures in a number and round values to a chosen number of significant figures. Users enter a value as written, including its zeros, and can review the result alongside a step-by-step explanation of how the digits were assessed. The tool supports common number formats, including decimals and scientific notation, and is useful for checking homework, laboratory calculations, and scientific work in chemistry, physics, engineering, and related fields.

The site also offers a practical learning guide covering what significant figures communicate about precision, how to identify leading, captive, and trailing zeros, and how to round numbers. Additional topics include the difference between significant figures and decimal places, rules for addition and subtraction, multiplication and division, measurements, and scientific notation. The calculator follows standard scientific conventions and references NIST guidance, while advising users to confirm results for graded or critical laboratory work with their instructor or lab manual.