Calculadora de Erro Percentual
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
erro% = |experimental − teórico| / |teórico| × 100
About this calculator
The Percent Error Calculator measures the difference between an experimental value and an expected or theoretical value, expressing this difference as a percentage of the theoretical value. The calculation uses the formula: percent error = |experimental value − theoretical value| / |theoretical value| × 100. The result indicates how close the experimental value is to the reference value, useful for assessing measurement accuracy or experimental precision.
To use the calculator, enter the experimental (measured) value and the theoretical (expected) value. The tool automatically applies the formula and returns the percent error. For example, if the theoretical value is 100 and the experimental value is 95, the percent error is 5%. This result can be interpreted as a 5% underestimation relative to the expected value.
This calculator is widely used in science labs, engineering, statistics, and quality control. It helps verify experiment validity, calibrate instruments, and compare results with standards. Common cases include checking the accuracy of a scale, measuring the precision of a chemical analysis, or evaluating the performance of a theoretical model.
Important precautions: the theoretical value cannot be zero, as division by zero is undefined. Additionally, the percent error can exceed 100% if the experimental value is far from the theoretical. Note that percent error does not indicate the direction of the error (over or under), only the relative magnitude.
Frequently asked questions
What does a negative percent error mean?
Percent error is always positive because it uses absolute value. If you need the direction of the error, use relative error without absolute value.
Can I use the calculator if the theoretical value is zero?
No. The theoretical value cannot be zero, as division by zero is undefined. In that case, percent error is not calculated.
What is the difference between percent error and absolute error?
Absolute error is the simple difference between values (without percentage), while percent error expresses that difference as a percentage of the theoretical value.
Does a high percent error always indicate a serious mistake?
It depends on the context. In high-precision measurements, a 1% error can be serious. In rough estimates, 10% may be acceptable. Evaluate the application.