How To Calculate Experimental Error in Chemistry

How To Calculate Experimental Error in Chemistry Error is a measure of the accuracy of the values in your experiment. It is important to be able to calculate experimental error, but there is more than one way to calculate and express it. Here are the most common ways to calculate experimental error: Error Formula In general, error is the difference between an accepted or theoretical value and an experimental value. Error Experimental Value - Known Value Relative Error Formula Relative Error Error / Known Value Percent Error  Formula % Error Relative Error x 100% Example Error Calculations Lets say a researcher measures the mass of a sample to be 5.51 grams. The actual mass of the sample is known to be 5.80 grams. Calculate the error of the measurement. Experimental Value 5.51 gramsKnown Value 5.80 grams Error Experimental Value - Known ValueError 5.51 g - 5.80 gramsError - 0.29 grams Relative Error Error / Known ValueRelative Error - 0.29 g / 5.80 gramsRelative Error - 0.050 % Error Relative Error x 100%% Error - 0.050 x 100%% Error - 5.0%