# Percent Error Calculator

> Work out the percent error between a measured or estimated value and the true, accepted value, plus the absolute error and its direction.

Category: Mathematics · Applies to: Worldwide · Last updated: 2026-10-29
Interactive calculator: https://calculators.geekmidst.com/calculators/percent-error-calculator

Percent error tells you how far a measurement is from the accepted value, as a percentage of that accepted value.

Also called: Percentage error calculator, Relative error calculator.

## Inputs
- Measured (experimental) value (default 52)
- True (accepted) value (default 50)

## Results
- Percent error
- Absolute error
- Signed percent error
- Direction

## Formula

```
Percent error = |Measured − True| ÷ |True| × 100
```

Where:
- Measured: the value you obtained
- True: the accepted or reference value

## Worked example
1. Absolute error = |52 − 50| = 2.
2. Percent error = 2 ÷ 50 × 100 = 4%.

**Result:** Measuring 52 when the true value is 50 is a 4% error, on the high side.

## What the result means

A small percent error means the result is accurate, not that it is precise: repeated measurements can all be close to each other and still share the same bias.

## Assumptions and limits
- The true value is known and is not 0.
- When the true value is 0 or very close to it, percent error is undefined or explodes; report the absolute error instead.

## Questions

### Can percent error be negative?

The usual definition uses the absolute value, so it is never negative. Some lab courses keep the sign to show whether the result was high or low; the calculator shows both.

### Is percent error the same as percentage change?

The arithmetic is similar, but percent error compares against a true value, while percentage change compares a new value against an old one.

## Related calculators
- [Percentage Change Calculator](https://calculators.geekmidst.com/calculators/percentage-change-calculator)
- [Percentage Calculator](https://calculators.geekmidst.com/calculators/percentage-calculator)
- [Statistics Calculator](https://calculators.geekmidst.com/calculators/statistics-calculator)

Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/percent-error-calculator