## Percentage Error

The formula for Percentage Error is
$\% Error = \frac{Observed, \: Estimated \:or \: Calculated Value -True \: Value}{True \: Value} \times 100 \%$
.
A Percentage error can be positive or negative depending on an over or underestimate/observation/calculation. Example: A plane is estimated to be 10km away when it is actually 8km away.
The percentage error is
$\frac{Estimated - True}{True} \times 100 \%= \frac{10-8}{8} \times 100 \%= 25 \%$