Mean Formula Explained

This reference explains the Mean formula used by our free Mean Calculator. Use it to understand variables, units, and common mistakes before you calculate.

The formula

x̄ = Σx ÷ n

Variables and units

• x̄ — Sample mean (average) (same as data)
• Σx — Sum of all values (same as data)
• n — Number of values (count)

Worked example

Inputs: Data set: 4, 7, 8, 12, 15

1. Σx = 4 + 7 + 8 + 12 + 15 = 46
2. n = 5
3. x̄ = 46 / 5 = 9.2

Result: Mean = 9.2

When to use this formula

Use this formula when you need a quick mean estimate with values you already know. Our Mean Calculator applies the same relationship automatically so you can verify handwritten work.

Common mistakes

• Including outliers without considering their impact
• Using mean for heavily skewed data (prefer median)
• Dividing by wrong count in grouped data

Frequently asked questions