To calculate the percentage of error, subtract the experimental value from the exact value, divide the difference by the exact value and multiply the final answer by 100 percent. You need to know the experimental value and the exact value to complete this task.
- Find the error
Subtract the experimental value from the exact value to get the error value.
- Divide the error by the exact value
Divide the error value by the exact value, and record the answer in decimal form.
- Calculate the percentage of error
Multiply the quotient in step two above by 100 percent to get the percentage of error. For instance, if the exact value is 30 and the experimental value is 27, the percentage of error is 10 percent.