It’s not uncommon to get an incorrect percentage when you estimate measurements. Let’s say you measure free fall timing to understand gravitational acceleration. The answer you measure will be different from the exact answer. If you want the percentage of error, you need to know the real and observed value.

You can find out the formula our **percent error calculator** uses below.
*The percent error = (TV – OV) / TV x 100%*
TV = true value
OV = observed value

Without a real-life example, you might not understand how percent error calculations work. Let’s say you want to know the relative error of the speed of sound. You would need to know the measured and actual values.
1. Identify the real value. If the air is 20 degrees-Celsius, it’s 343 m/s.
2. Identify your value. You thought it was 333 m/s.
3. Take your value away from the real value.
*343 – 333 = 10 m/s*
4. 10 m/s is the error, but you need it as a percentage. Divide it by the real value.
*The percent error = 10 / 343 x 100% = 2.915 percent*.