Percent Error Calculator

About the Percent Error Calculator

This calculator determines the percentage error between an observed (measured) value and a true (accepted) value. Percent error is a measure of how inaccurate a measurement is, standardized to how large the measurement is.

How It Works

The calculator uses the following formula to compute percent error:

Percent Error = |(Observed Value - True Value)| / |True Value| × 100%

Where:

• Observed Value is the measured experimental value
• True Value is the known or theoretical value
• The absolute value ensures the result is always positive

When to Use Percent Error

Percent error is commonly used in:

• Scientific experiments to assess measurement accuracy
• Quality control in manufacturing processes
• Comparing experimental results to theoretical predictions
• Assessing the reliability of measurement instruments

Interpreting Results

The percent error indicates how far the observed value deviates from the true value:

• 0% error: Perfect measurement (observed = true)
• Small error (<5%): Generally considered acceptable in many fields
• Large error (>10%): May indicate measurement problems or flawed assumptions

Limitations

While percent error is a useful metric, it has some limitations:

• Can be misleading when the true value is very small (approaches zero)
• Doesn't account for systematic errors (bias) in measurements
• Should be interpreted in context with other statistical measures