Significant Figures Calculator
Preserve the written decimal input to count significant figures and apply precision rules. Round mode uses a chosen figure count; addition/subtraction uses decimal place precision, while multiplication/division uses the least precise significant-figure count.
Your result
How the calculation works
For addition/subtraction, retain the coarsest input decimal place. For multiplication/division, retain the fewest significant figures. Round ties away from zero using exact rational arithmetic before display.
Worked example
0.004560 has four significant figures and rounds to 0.00456 at three figures. 1.20×2.0 becomes 2.4 at two significant figures; 1.20+2.0 becomes 3.2 at one decimal place.
Assumptions and limitations
Plain integer trailing zeros are ambiguous; this tool treats them as significant and warns. Scientific notation explicitly communicates precision. Zero uses the written fractional precision; bounds match the notation tool.
Rounding conventions differ between disciplines. This tool uses half-away-from-zero rather than banker’s rounding. Keep unrounded intermediate values when your protocol requires rounding only at the end.
Sources and editorial responsibility
Maintained by Renvoro Pty Ltd. Sources inform the methods and assumptions shown here; outputs have the limitations described on this page.
Method reviewed 2026-10-13. Calculation standards · Report an issue