Finding Percent Error Units to compare: English Unit yards to feet to inches to Metric Unit meters decimeters centimeters In a perfect world, there are actually: 0.91 meters in one yard 3.048 decimeters in one foot 2.54 centimeters in one inch To find percent error: Step 1: Take your metric measurement divided by your English measurement. Height of book: 11.2 inches 28.3 centimeters 28.3 ÷ 11.2 = 2.53 Step 2: Take your result minus the actual number for the units you are using. Actual for inches and centimeters is 2.54. 2.53 – 2.54 = -0.01 Step 3: You might end up with a negative number, so take the negative sign off. -0.01 = 0.01 Step 4: Take your result divided by the actual number for the units you are using. 0.01 ÷ 2.54 = 0.0039 Step 5: Change this number into a percent by multiplying it by 100 (or by moving the decimal point two places to the right – same answer) 0.0039 x 100 = 0.39% Step 6: Check. Is your answer less than 10%? For this lab, having less than 10% error is okay.