Compare your experimental measurement against the true value.
Percent error measures how far a measured value deviates from the true or accepted value. It is commonly used in scientific experiments, manufacturing quality control, and statistical analysis.
Percent Error = |Experimental − Theoretical| / |Theoretical| × 100%. If the experimental value is lower, it is an underestimate; if higher, an overestimate.
Percent error compares a measured value to an accepted reference value. Percent difference compares two equally-valid measurements against their average. Percent error uses |measured − true| / |true|, while percent difference uses |a−b| / ((a+b)/2).
By convention, percent error is reported as an absolute value (always positive). However, some contexts report signed percent error: positive when the experimental value exceeds the theoretical value (overestimate), and negative when it falls short (underestimate).