1. What is Error Percentage?

Error percentage is a measure of how inaccurate a predicted value is compared to the actual value. It quantifies the difference between what was expected and what actually occurred, expressed as a percentage of the actual value.

2. How Does the Calculator Work?

The calculator uses the error percentage formula:

Where:

• \( Actual \) — The measured or true value
• \( Predicted \) — The estimated or forecasted value

Explanation: The formula calculates the absolute difference between actual and predicted values, divides by the actual value to get a relative error, then converts to percentage.

3. Importance of Error Percentage

Details: Error percentage is widely used in statistics, engineering, forecasting, and quality control to assess the accuracy of predictions and measurements.

4. Using the Calculator

Tips: Enter both actual and predicted values. The actual value must be greater than zero. The result shows what percentage the prediction was off from reality.

5. Frequently Asked Questions (FAQ)

Q1: What's a good error percentage?
A: This depends on context. In some fields <5% is excellent, while others may tolerate 10-20%. Compare against industry standards.

Q2: Can error percentage be negative?
A: No, because we use absolute value in the numerator. The direction of error isn't shown, only magnitude.

Q3: What if actual value is zero?
A: The formula is undefined when actual=0. Use alternative metrics like absolute error in such cases.

Q4: How does this differ from percent difference?
A: Percent difference compares two experimental values, while error percentage compares to a known reference.

Q5: When shouldn't I use this?
A: When actual values are very small or zero, or when relative error isn't the most meaningful metric.