What is the difference between percentage difference and percentage change?

Percentage change compares a new value to an original value (used for growth or decline). Percentage difference compares two values without a clear original, using the average as the base.

Does order matter in percentage difference?

No. Percentage difference between 20 and 30 is the same as between 30 and 20. Order only matters for percentage change.

How-To Guide

How to Calculate Percentage Difference

Percentage difference measures how far apart two numbers are, using their average as the base. Here's the formula with three worked examples.

📋 What You'll Need

Two numbers to compare
Basic arithmetic (add, subtract, divide, multiply)
A calculator — or use our free percentage calculator

The Formula

% Difference = (|A − B| ÷ ((A + B) ÷ 2)) × 100

Find the Absolute Difference

Subtract one value from the other, then take the absolute value:

|A − B|

Example: for 80 and 100, |80 − 100| = 20.

Find the Average

Add the two values together and divide by 2:

(A + B) ÷ 2

Example: (80 + 100) ÷ 2 = 90.

Divide and Multiply by 100

Divide the difference by the average, then multiply by 100:

(difference ÷ average) × 100

Example: (20 ÷ 90) × 100 = 22.22%.

💡 Quick check: the result is always positive. If you got a negative number, you forgot the absolute value step.

🧮 Worked Examples

Example 1 — Comparing Prices

A laptop costs $900 at one store and $1,100 at another.

Step 1: |900 − 1100| = 200

Step 2: (900 + 1100) ÷ 2 = 1000

Step 3: (200 ÷ 1000) × 100 = 20%

→ 20% difference

Example 2 — Comparing Test Scores

Two students score 72 and 88 on the same exam.

Step 1: |72 − 88| = 16

Step 2: (72 + 88) ÷ 2 = 80

Step 3: (16 ÷ 80) × 100 = 20%

→ 20% difference

Example 3 — Comparing Measurements

Two batches of dough weigh 350 g and 410 g.

Step 1: |350 − 410| = 60

Step 2: (350 + 410) ÷ 2 = 380

Step 3: (60 ÷ 380) × 100 = 15.79%

→ 15.79% difference

⚖️ Percentage Difference vs. Percentage Change

Percentage Change

Compares a new value to an original value. Order matters. Can be positive or negative. Formula: ((new − old) ÷ old) × 100.

Percentage Difference

Compares two values with no assumed order. Always positive. Uses the average as the base. Formula: (|A − B| ÷ ((A + B) ÷ 2)) × 100.

💡 Rule of thumb: use percentage change when there's a clear "before and after." Use percentage difference when comparing two things side by side.

🚫 Common Mistakes to Avoid

Forgetting the absolute value. Without it, the result can be negative — but percentage difference is always positive.
Using the wrong base. Percentage difference uses the average, not the original value.
Dividing by the sum instead of the average. The correct denominator is (A + B) ÷ 2, not A + B.
Confusing it with percentage error. Percentage error compares to a "true" value; percentage difference compares two measured values.