Percent Error Calculator Online Free
Percent Error Calculator
Calculate Percentage Error
The value you measured or observed
The expected, accepted, or known value
The percent error calculator measures how far an experimental or estimated value is from the true or accepted value, expressed as a percentage. It is used in science, engineering, and statistics to evaluate measurement accuracy and experimental precision.
Percent Error Formula
Divide the absolute difference between the experimental and accepted values by the accepted value, then multiply by 100. The result shows what percentage of the true value the error represents.
Percent Error = |Experimental − Accepted| / |Accepted| × 100%
Use absolute values so the result is always positive. Some applications report signed percent error to show direction.
What Counts as Acceptable Percent Error
Acceptable error depends on the field. Physics lab experiments often aim for under 5%. Medical measurements may require under 1%. Engineering tolerances are defined by safety requirements. Chemistry titrations typically achieve under 0.1%. Compare your result to the standard for your specific application.
Frequently Asked Questions
What does a high percent error mean?⌄
A high percent error means the measured or calculated value differs significantly from the accepted value. It may indicate measurement error, faulty equipment, incorrect methodology, or an inaccurate model.
Can percent error be negative?⌄
If you do not take the absolute value, percent error can be negative when the experimental value is less than the accepted value. Signed percent error indicates whether the measurement overestimates or underestimates the true value.
What is the difference between percent error and percent difference?⌄
Percent error compares a measured value to a known true value. Percent difference compares two measured values when neither is considered the definitive correct answer, using their average as the reference.