# Percent (%) Error Calculator

getcalc.com's Error Percentage Calculator is an online basic math functions tool to find the difference between observed (practical) & theoretical (expected) score in percentage with respect to theoretical score. To calculate X% of Y, X is what percentage of Y, percentage difference, change, increase or decrease, use the below calculators

## Definition & Formulas

**Error Percentage** is an important mathematical function used to measure the practical and theoretical values difference in percentage with respect to the theoretical value. For example, the expected radius of a machining bolt is 9 inches but the observed is 8.7 inches, then what is the error percent? The answer is 3 percent. Similarly, the percent error is applicable in most of the applications wherever the expected & observed score is comes into effect. It’s mostly used in the field manufacturing, finance, statistics etc.