# What is the Formula for Percent Deviation?

The word “percent deviation” is used in statistics and many scientific fields to indicate how inaccurate test results may be. You need a calculator and a reference standard to calculate percent deviation.

## Compared to the norm, compare your data

You are frequently given a benchmark or a theoretical consequence to anticipate from your data in experiments or data-recording tasks. For instance, it is well known that the acceleration caused by gravity is 9.8 m/s2 in a physics lab that calculates the acceleration of a falling item.

However, your calculated result could not be 9.8 m/s2 precisely due to minute discrepancies in calculations of the distance or time to fall. Check how closely your outcome matches the benchmark after you’ve finished your calculations and experiment.

## Find the distinction

By deducting the smaller of the two from the larger, you may determine the discrepancy between your calculation and the norm. If you discovered 9.5 m/s2, for instance, the calculation for the difference is 9.8 m/s2 – 9.5 m/s2 = 0.3 m/s2.

## Do the % deviation calculation.

The percent deviation is calculated by multiplying your data by the standard deviation by 100 and then dividing the result by 100. (|data – standard|) 100 * / (standard) The formula is expressed as follows for the acceleration experiment: 100 * (9.8 – 9.5)/(9.8) = 100 * (0.3)/9.8 = 3.06% Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.