statistics calculator

Standard Deviation Calculator

Measure how spread out your data is from the average. Crucial for statistics, quality control, finance, research — anywhere you need to understand variability.

Important Use Notice

Informational calculator only. Verify important outputs independently before legal, tax, medical, engineering, safety-critical, contractual, employment, or compliance use.

Estimate

Enter job values, review the estimate, then use the decision hints before ordering or quoting.

Enter numbers separated by commas

Estimate Results

Enter values to see the result.

Check

Using population vs sample standard deviation incorrectly
Forgetting to square differences

Example

Scores: 85, 90, 88, 92, 87 → mean 88. 4, std dev ≈ 2. 51

Formula

σ = √[ Σ(xi - μ)² / N ]

μ — mean, xi — each value, N — number of values. This is population standard deviation (divide by N). For sample, divide by N-1.

Variance = σ²

Next Step

FAQ

Population vs sample standard deviation?

Use population (divide by N) for entire dataset; sample (divide by N-1) for estimates from a sample.

What does a low standard deviation mean?

Data points are clustered close to the mean — low variability.