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Percent Error Calculator

Deviation of measurement from accepted value.

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Frequently asked questions

What is acceptable % error?
Depends on application. Chemistry lab: <2%. Engineering: <0.1% for precision work. School physics experiments: <5% usually acceptable.
% error vs uncertainty?
% error compares to known true value. Uncertainty expresses range of possible values when true is unknown (e.g., ± 0.5).
Can error be negative?
Signed error yes (measured − true). % error is usually absolute (positive).
Sources of error?
Instrument precision, calibration, human reading, environmental factors, systematic bias. Identify and minimize each.