Percentage Error Calculator

Percentage Error Calculator is designed for the exact search intent behind “percent error calculator”. Calculate the percent error between an experimental or observed value and an accepted reference value. The result shows the size of the error relative to the accepted value. Calculate percent error between an experimental/observed value and an accepted/theoretical value. Percent error formula The common unsigned formula is Percent error = |experimental − accepted| ÷ |accepted| × 100% . The absolute difference makes the usual reported percent error non-negative. If direction matters, keep the signed difference separately rather than treating it as the standard absolute percent-error result. How to calculate percent error Subtract the accepted value from the experimental value. Take the absolute value of that difference. Divide by the absolute accepted value. Multiply by 100 to express the result as a percentage. Percent error vs. percent difference Percent error is appropriate when one value is treated as the accepted or reference value. Percent difference is commonly used when comparing two measurements without designating either one as the true reference, and typically uses their average in the denominator. Worked example: If an experiment measures 9.70 and the accepted value is 9.81, percent error = |9.70 − 9.81| ÷ 9.81 × 100 ≈ 1.12%. Common practical uses include Compare an experimental measurement with an accepted value; Check physics or chemistry lab calculations; Measure relative error in engineering or calibration work; Review quality-control measurements against a reference. Important limitations: The usual relative percent-error formula is undefined when the accepted value is zero. Percent error measures closeness to a chosen reference; it does not by itself measure repeatability, uncertainty or experimental precision. Rounding inputs too early can change the displayed percentage. Key questions this page should answer include: What is the formula for percent error? |experimental − accepted| ÷ |accepted| × 100%. Can percent error be negative? The common percent-error formula uses an absolute difference, so its result is non-negative. A signed relative error is a different convention. What is the difference between percent error and percent difference? Percent error compares a measurement with an accepted reference. Percent difference generally compares two peer values using their average as the reference. What if the accepted value is zero? The usual formula cannot divide by zero, so a different absolute or domain-specific error measure is required. Is a lower percent error always better?

How to use this tool

Percent error formula

The common unsigned formula is Percent error = |experimental − accepted| ÷ |accepted| × 100%.

The absolute difference makes the usual reported percent error non-negative. If direction matters, keep the signed difference separately rather than treating it as the standard absolute percent-error result.

How to calculate percent error

1. Subtract the accepted value from the experimental value.
2. Take the absolute value of that difference.
3. Divide by the absolute accepted value.
4. Multiply by 100 to express the result as a percentage.

Percent error vs. percent difference

Percent error is appropriate when one value is treated as the accepted or reference value. Percent difference is commonly used when comparing two measurements without designating either one as the true reference, and typically uses their average in the denominator.

Examples

Common use cases

• Compare an experimental measurement with an accepted value
• Check physics or chemistry lab calculations
• Measure relative error in engineering or calibration work
• Review quality-control measurements against a reference

Frequently asked questions