Percentage error is found by dividing the error amount by the original estimate, then multiplying that result by 100%.
Note: the percent error measures FROM the first value. An error of 25 from an estimate of 50 25 is 50%. If that error were looked at from the perspective of the actual amount (75) it would be a different percentage change (an error of 25 from a result of 75 is a difference of 33.3%).
Error of 25 from an estimate of 50:
Error of 25 from an estimate of 75:
Error of 0.0001 from an estimate of 0.0443
What is a percentage?
A percentage is a number expressed as a fraction of 100.
If a number is 100% (100 percent), then it is a “whole” – the same as one.
If a number is 50%, then it is a half – the same as 0.5 or 1/2.
If a number is 400%, then it is 4 times, the same as 4.