Variance Calculator

Published on: August 24, 2025

Enter numbers separated by commas to compute the population variance.

Step-by-step method

  1. List the numbers and calculate the mean (μ).
  2. Find each deviation from the mean (x − μ).
  3. Square each deviation.
  4. Average the squared deviations to get the population variance.

Formula:

σ²=
Σ(x − μ)²
n

Example 1: 3, 1, 4, 2

Step 1 - List the numbers and calculate the mean (μ).

In this problem: The numbers are 3, 1, 4, 2. The mean is μ = Σx ÷ n with n = 4.

Σx=10,n=4μ=2.5

Step 2 - Find each deviation from the mean (x − μ).

In this problem: Subtract the mean from each value: x − μ using μ = 2.5.

Deviations=[0.5, -1.5, 1.5, -0.5]

Step 3 - Square each deviation.

In this problem: Square each deviation to remove negatives.

(x − μ)²=[0.25, 2.25, 2.25, 0.25]

Step 4 - Average the squared deviations to get the population variance.

In this problem: Add the squared deviations and divide by n = 4: σ² = Σ(x − μ)² ÷ n.

Σ(x − μ)²=5σ²=5÷4=1.25

Final answer: Variance = 1.25

Example 2: 5, 6, 7, 8, 9

Step 1 - List the numbers and calculate the mean (μ).

In this problem: The numbers are 5, 6, 7, 8, 9. The mean is μ = Σx ÷ n with n = 5.

Σx=35,n=5μ=7

Step 2 - Find each deviation from the mean (x − μ).

In this problem: Subtract the mean from each value: x − μ using μ = 7.

Deviations=[-2, -1, 0, 1, 2]

Step 3 - Square each deviation.

In this problem: Square each deviation to remove negatives.

(x − μ)²=[4, 1, 0, 1, 4]

Step 4 - Average the squared deviations to get the population variance.

In this problem: Add the squared deviations and divide by n = 5: σ² = Σ(x − μ)² ÷ n.

Σ(x − μ)²=10σ²=10÷5=2

Final answer: Variance = 2