# Percent Error Calculator Calculate percent error between an experimental value and a reference value > Canonical page: https://elysiatools.com/en/tools/percent-error-calculator - **Category:** Math & Numbers - **Keywords:** percent error, measurement error, lab calculator ## Overview The Percent Error Calculator is a straightforward utility designed to determine the accuracy of a measurement. By comparing an experimental value to a known reference value, it instantly calculates both the absolute error and the percent error. This tool is ideal for students, scientists, engineers, and analysts who need to quantify the precision of their lab results, manufacturing tolerances, or data forecasts. ## Inputs - **Experimental Value** (text): e.g. 9.8 - **Reference Value** (text): e.g. 10 - **Decimal Places** (number) ## When to use - When evaluating the accuracy of experimental data against accepted theoretical values in laboratory reports. - When calibrating instruments or machinery to ensure measurements fall within an acceptable margin of error. - When analyzing statistical forecasts or financial estimates compared to actual observed outcomes. ## How it works - Enter your measured or observed result into the Experimental Value field. - Input the accepted or theoretical target into the Reference Value field. - Adjust the Decimal Places setting to control the precision of your final output (between 0 and 12). - The calculator instantly processes the inputs to return the absolute error and percent error in a structured format. ## Use cases - Chemistry and physics students calculating the accuracy of their lab experiment results against known constants. - Quality control inspectors verifying that manufactured parts meet exact dimensional specifications. - Data analysts measuring the variance between projected sales figures and actual revenue. ## Frequently asked questions ### What is the formula for percent error? Percent error is calculated by subtracting the reference value from the experimental value, taking the absolute value of the result, dividing by the absolute reference value, and multiplying by 100. ### Can the percent error be negative? Standard percent error is expressed as a positive percentage because it uses the absolute difference. The absolute error provided by the tool also represents the magnitude of the difference without a sign. ### What does a low percent error mean? A low percent error indicates that your experimental value is very close to the accepted reference value, meaning your measurement or estimate is highly accurate. ### How many decimal places can I calculate? You can configure the calculator to output results with anywhere from 0 to 12 decimal places, depending on the precision required for your specific use case. ### Is this tool suitable for chemistry and physics labs? 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