Calculate percent difference between two values using the average method. Compare measurements symmetrically with step-by-step solutions.
Percent Difference
18.18%
First value to compare (should be positive)
Second value to compare (should be positive)
Step 1: Identify the values
V1 = 100, V2 = 120
Step 2: Calculate the absolute difference
|V1 - V2| = |100 - 120| = 20
Step 3: Calculate the mean (average)
(V1 + V2) / 2 = (100 + 120) / 2 = 110
Step 4: Divide difference by mean and multiply by 100
20 / 110 x 100 = 18.18%
Percent Difference = 18.18%
| Scenario | Use | Why |
|---|---|---|
| Price went from $50 to $60 | Percent Change | Clear before/after relationship |
| Comparing two lab measurements | Percent Difference | Neither is the "true" value |
| Measured 9.8, expected 9.81 | Percent Error | Comparing to known/accepted value |
| Comparing two estimates | Percent Difference | Both are equally valid estimates |
Percent Difference
18.18%
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Practice with 4 problems to test your understanding.
Percent difference measures how different two values are relative to their average. Formula: |V1 - V2| / ((V1 + V2) / 2) x 100%. For example, comparing 10 and 14: |10 - 14| / ((10 + 14) / 2) x 100% = 4 / 12 x 100% = 33.33% difference. Unlike percent change, this is symmetric - the order doesn't matter.
Percent difference calculates how different two values are relative to their average, expressed as a percentage. Unlike percent change, it is symmetric - swapping the two values gives the same result. This makes it ideal for comparing two measurements where neither is considered the 'correct' or 'reference' value, such as comparing two experimental results or two competing estimates.
Percent difference measures how different two values are relative to their average. Formula: |V1 - V2| / ((V1 + V2) / 2) x 100%. For example, comparing 10 and 14: |10 - 14| / ((10 + 14) / 2) x 100% = 4 / 12 x 100% = 33.33% difference. Unlike percent change, this is symmetric - the order doesn't matter.
Percent difference measures how different two values are, relative to their average. The formula is: |V1 - V2| / ((V1 + V2) / 2) x 100%. It is always positive and symmetric, meaning the order of the values does not affect the result.
Percent change measures directional change FROM an original TO a new value, using the original as the reference. Percent difference compares two values without a reference point, using their average. Use percent change when you have before/after; use percent difference when comparing two measurements.
Percent error compares a measured value to a known/accepted value (the "truth"). Percent difference compares two values where neither is considered "correct" - for example, comparing two experimental measurements. Error uses theoretical value as denominator; difference uses average.
The formula works best with positive values because the mean (average) is used as the reference. If values have opposite signs, the mean could be zero or very small, leading to extremely large or undefined percent differences. The formula is designed for comparing magnitudes.
The percent difference approaches 200% as one value approaches zero while the other remains positive. For example, comparing 0.001 and 100: the difference is large relative to the mean. If both values are identical, percent difference is 0%.
Last updated: 2025-01-15
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Percent Difference
18.18%