Coefficient of Variation Calculator
Comparing Spread Across Completely Different Scales
Standard deviation alone can't tell you whether $50 of variation in a $10,000 salary is more or less significant than $50 of variation in a $200 grocery bill — the raw numbers aren't comparable. The coefficient of variation fixes this by expressing spread as a percentage of the mean, making it possible to compare variability across data sets measured in entirely different units or magnitudes.
The Formula
Because it's a ratio, the units cancel out — CV is always expressed as a unitless percentage, which is exactly what makes it comparable across data sets that standard deviation alone cannot compare directly.
Same Relative Spread, Different Scale
| Data set | Mean | Std Dev | CV |
|---|---|---|---|
| 10, 12, 9, 11, 13 | 11.0 | 1.58 | 14.37% |
| 100, 120, 90, 110, 130 | 110.0 | 15.81 | 14.37% |
The second data set has ten times the standard deviation of the first, which looks far more variable at a glance — but the CV shows they're proportionally identical, because every value was simply scaled up by 10.
Where This Matters
- Investment analysis — comparing risk-per-unit-of-return across assets with very different price levels.
- Laboratory and scientific measurement — assessing measurement precision (repeatability) independent of the units being measured.
- Quality control — comparing consistency of a manufacturing process across product lines with different target dimensions.
- Cross-study comparison — comparing variability findings from research that used different units or scales for the same underlying concept.
How to Use This Calculator
- Choose Sample-based or Population-based calculation from the dropdown.
- Enter your numbers into the values field, separated by commas.
- Select Calculate to get the CV as a percentage.
Related Calculations
See the underlying spread with the Standard Deviation Calculator, or the central value it's measured against with the Mean Calculator.