# Percent Error Calculator

URL: https://speedycalculator.com/calculators/math/percent-error/
Last updated: 2026-10-25

> The percent error calculator compares a measured or estimated value with the true or accepted value and expresses the difference as a percentage of the true value.

## Inputs

- Measured value
- True value

## Results

- Percent error
- Absolute error
- Signed relative error

## Formula

```
Percent error = |measured − true| ÷ |true| × 100
```

## Explanation

Percent error is standard in science labs for judging how close an experimental result is to the accepted value.

### How to use the Percent Error Calculator

- **Measured value**
- **True value**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Subtract the true value from the measured value, take the absolute value and divide by the true value.

### Inputs explained

FieldWhat to enterMeasured valueA numberTrue valueA number

### What each result means

- **Percent error** = abs([Measured value] - [True value])÷abs([True value]) × 100
- **Absolute error** = abs([Measured value] - [True value])
- **Signed relative error** = ([Measured value] - [True value])÷[True value] × 100

### Example values

How the main result changes when **Measured value** changes and everything else stays at the example values above:

Measured valuePercent error (%)4.851.07037.226.60559.62.14071222.324214.446.78919.295.7187

## Worked example

Inputs — Measured value: 9.6; True value: 9.81.

Results — **Percent error = 2.1407 %**; Absolute error = 0.21; Signed relative error = -2.1407 %.

## FAQ

**Why use absolute value?**
Percent error usually ignores direction; the signed error shows over- or under-estimation.

**What is a good percent error?**
Depends on the experiment; under 5% is often acceptable in school labs.

**What formula does the Percent Error Calculator use?**
Percent error = |measured − true| ÷ |true| × 100.