The coefficient of variation calculator computes CV% — the ratio of standard deviation to the mean. Use it to compare variability across datasets with different units or scales, such as comparing investment risk, quality control measurements, or scientific data consistency.
Coefficient of Variation Calculator
How to Calculate Coefficient of Variation
The coefficient of variation (CV) formula is: CV = (Standard Deviation ÷ Mean) × 100%. It expresses spread as a percentage of the average, making it a unitless measure you can use to compare apples to oranges — say, stock volatility vs. weight measurements.
Step 1: Enter Your Data
Paste or type your numbers into the input box. Separate values with commas, spaces, or line breaks. The tool accepts up to thousands of values. Try the preset examples to see how different datasets produce different CV results.
Step 2: Read the Results
The calculator shows Sample CV (recommended for most use cases) and Population CV. Sample CV uses Bessel's correction (N−1) for an unbiased estimate when your data is a sample from a larger population. The interpretation guide tells you whether the variability is low, moderate, or high.
Interpreting CV Values
As a rule of thumb: CV below 15% indicates low variability (data is consistent), 15–30% is moderate variability (some spread around the mean), and above 30% is high variability (data is quite spread out). In quality control, processes typically aim for CV below 5%. In biological research, CV of 10–20% is often acceptable. In finance, a lower CV means better risk-adjusted return.
When CV Is Undefined
If the mean equals zero, CV is mathematically undefined (division by zero). CV also loses practical meaning near zero means or with negative mean values. In these cases, use absolute standard deviation or interquartile range instead.
FAQ
What is the coefficient of variation?
The coefficient of variation (CV) is the ratio of the standard deviation to the mean, expressed as a percentage: CV = (SD / Mean) × 100. It measures relative variability — how large the spread is relative to the average. Unlike raw standard deviation, CV is unitless, so you can compare variability across datasets with different units or scales.
What does a CV of 15% mean?
A CV of 15% means the standard deviation is 15% of the mean. In practice: CV < 15% indicates low variability (consistent data), 15–30% is moderate variability, and >30% is high variability. For example, a quality-controlled manufacturing process should have CV < 5%, while biological measurements often range 10–30%.
When should I use population vs sample CV?
Use population CV when your dataset represents the entire population. Use sample CV (default) when your data is a subset — this is most common in research and quality control. Sample CV uses N−1 (Bessel's correction) in the denominator, giving a slightly larger, more conservative estimate.
Can I calculate CV when the mean is zero?
No — CV is undefined when the mean equals zero because dividing by zero is mathematically undefined. CV also loses meaning when the mean is negative or near zero. In such cases, consider using standard deviation alone or switching to a different variability measure like the interquartile range.
How is CV used in finance?
In finance, CV measures risk-adjusted return. If Stock A has mean return 10% with SD 5% (CV=50%) and Stock B has mean return 20% with SD 8% (CV=40%), Stock B is more efficient — less relative risk per unit of return. CV is preferred over raw SD for comparing assets with different expected returns.
Is this calculator free?
Yes, completely free with no signup required. All calculations run in your browser — no data is transmitted anywhere.
Is my data private?
Yes. Everything runs locally in your browser. Your dataset is never sent to any server.