ZovaTool

Percent Error Calculator

Result

Percent Error
5%
Accuracy
95%
Difference
5
Relative Error
0.05
Grade
Acceptable

Step-by-step

Step 1
Difference = Observed − Expected = 105 − 100 = 5
Step 2
|Diff| ÷ |Expected| = 5 ÷ 100 = 0.05
Step 3
× 100% = 5%

How to use the Percent Error Calculator

  1. Enter the theoretical (expected) value.
  2. Enter the experimental (observed) value.
  3. Toggle absolute vs signed if you want to keep direction information.
  4. Result shows percent error, accuracy, raw difference and relative error.
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Why percent error matters

Percent error compares an experimental measurement to a known or accepted value. The standard formula is |observed − expected| / |expected| × 100%.

Use the signed version when the direction of the deviation matters (e.g. is your scale reading high or low?). The absolute version is more common in lab reports and physics class.