Toolvica

Percentage Error Calculator

Find the percentage error between measured and actual values. Free, fast, and accurate.

Percentage Error

Find the error between measured and actual values

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About

The Percentage Error Calculator measures how far a measured or experimental value is from the true or accepted value. Perfect for lab experiments, manufacturing tolerances, quality control, and scientific measurements.

How to Calculate Percentage Error

Percentage error measures how far a measured or experimental value is from the true or accepted value.

|Measured − Actual| / Actual × 100

You measure a length as 105 cm, but the actual length is 100 cm.

  1. Find the difference: 105 − 100 = 5
  2. Take the absolute value: |5| = 5
  3. Divide by the actual value: 5 ÷ 100 = 0.05
  4. Multiply by 100: 0.05 × 100 = 5%

Our calculator above automates this process. Simply enter the measured and actual values and the result appears instantly with a full step-by-step breakdown.

Real-World Examples

Recipe Scaling

A recipe needs 250g flour but you used 270g. Enter 270 and 250. Error: 8%.

GPS Distance

GPS shows 5.2 km but the actual distance is 5 km. Enter 5.2 and 5. Error: 4%.

Fitness Tracker

Your watch logged 8,500 steps but you actually took 8,000. Enter 8500 and 8000. Error: 6.25%.

Fuel Gauge

Your tank shows 60% full but actually has 55% fuel. Enter 60 and 55. Error: 9.09%.

Shopping Estimate

You estimated $150 for groceries but spent $172. Enter 150 and 172. Error: 12.79%.

Weather Forecast

Forecast said 30°C but actual was 27°C. Enter 30 and 27. Error: 11.11%.

FAQ

What is percentage error used for?
Percentage error measures how accurate a measurement or estimate is compared to the true value. It's used in science, cooking, fitness tracking, and any situation where you compare an approximate value to the actual value.
How do I use this calculator?
Enter your measured or estimated value in the first field and the actual or accepted value in the second field. The calculator shows how far off your measurement is as a percentage.
What does a 0% error mean?
A 0% error means your measured value matches the actual value exactly. This is rare in real-world measurements but indicates perfect accuracy.
Can percentage error be negative?
No. Percentage error is always positive because it uses the absolute difference. It tells you how far off you are, regardless of direction (over or under).
What's a good percentage error?
It depends on the context. In science, under 5% is often acceptable. For everyday estimates, under 10% is reasonable. The lower the percentage, the more accurate your measurement.