Percent Error Calculator

You can use the percent error calculator to quickly and easily compute the percentage error between the true and observed values of a measurement.

Simply input the accepted (true) value and the observed value and click on the "Calculate" button. The results will be automatically generated.

Percent Error Calculator

What is Accepted Value?

The accepted value, or true value, of a measurement, is required to determine the error of a measurement. By comparing a measurement with the accepted value, it is possible to calculate the error in the measurement.

What is Observed Value?

The observed value is the measurement that is physically recorded during an experiment. It is also commonly referred to as the experimental value.

What is a Measurement Error?

The difference between the observed value and the accepted (true) value is the error of a measurement. It is calculated by determining the difference between the accepted value and the observed value, or vice versa.

Error = | (Observed Value - Accepted Value) |

The measurement error is equal to the absolute value of the difference between the accepted and observed values. As such, it is neither negative or positive.

What is Percent Error?

The percent error of a measurement provides an indication of the extent to which the actual measurement taken during an experiment agrees with an accepted value of an equal amount. It is determined by dividing the error by the accepted value and then converting this figure to a percentage by multiplying it by 100:

Percent Error = Error / Accepted Value × 100

Percent Error = | (Observed Value - Accepted Value) / Accepted Value | × 100

Example:  Let's say a scientist takes a measurement of the density of an object and determines that it is 3600 grams per cubic decimeter. The accepted density of the object is 4600 grams per cubic decimeter.

The percent error of the measurement can be determined as follows:

Percent Error = | (Observed Value - Accepted Value) / Accepted Value | × 100

Percent Error = | (3600 g/dm3 - 4600 g/dm3) / 4600 g/dm3 | × 100

= | -1000 g/dm3 / 4600 g/dm3 | × 100

= 21.74%.

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