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It's much more challenging to determine whether a specific absolute error is of sufficient accuracy. The main advantage of the relative error is that, since it can only take values between 0-100%, it's easy to evaluate whether an error is big or small. To know more about calculating percentage error, check our percent error calculator.

Whether you're analysing length, weight, or temperature, the unit doesn't influence the result. The relative error is |(121.2 - 120.5) / 121.2| = 0.00578 = 0.578%Īs you can see, the relative error is expressed as a percentage and is unitless. When you measure your child at home, you find the measured value to be 120.5 cm. For example, let's say you measure your child's height in a doctor's office to the highest degree of accuracy, so the actual value it's equal to 121.2 cm. The relative error compares the absolute error to the actual value of the property you're measuring. Relative error = |absolute error / actual value| = |(actual value - measured value) / actual value|īoth the absolute and relative errors are typically expressed as positive values, hence the use of absolute values. Relative error (or percent error), on the other hand, expresses the error in terms of a percentage.

For example, if you measured the height of a tree in feet, the absolute error would also be expressed in feet. Remember that the absolute error is expressed in the same unit as the measured and real values. The actual value will be somewhere between 139.5 and 141.5 lbs. 140 lbs, you can say that your weight is 140 ± 0.5 lbs, with the measured value equal to 140 lbs and the absolute error equal to 0.5 lb. For example, imagine that you have a bathroom scale that only displays the result in full pounds - it can't get more accurate than that. Very often, we speak about absolute error to indicate how inaccurate a measuring device is. The measured value, on the other hand, is an approximation. The actual value is otherwise known as the real or true value. You can express it with the following equation:Ībsolute error = |actual value - measured value| Absolute error, also called the approximation error, is the absolute value of the difference between the actual value and the measured value.