Percent Error and Significant Figures Calculator
Calculate the percent error of a measurement, or count and round significant figures — two everyday tools for science and lab work.
Result
Enter values to compare or a number to inspect.
How to use this calculator
- Percent error: enter the measured and accepted values.
- Significant figures: enter a number as written (keep trailing zeros) and optionally a number of figures to round to.
Formula
Percent error = |measured − accepted| ÷ |accepted| × 100. Significant figures: leading zeros never count, zeros between digits do, and trailing zeros count only after a decimal point.
Worked example
Examples
A measured 9.8 against 10 is a 2% error. 0.00450 has 3 significant figures; 1200 has 2 (ambiguous) and 1200. has 4.
Assumptions and limitations
- Everything runs in your browser; nothing you enter is uploaded or stored.
- Numbers like 1200 are ambiguous without a decimal point or scientific notation.
Frequently asked questions
Can percent error be negative?
Percent error uses the absolute value, so it is never negative. The result also says whether the measurement was above or below.
How do I show trailing zeros are significant?
Use a decimal point (1200.) or scientific notation (1.20 × 10³).