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Percentage Difference Calculator

Compare two numbers on equal terms. The gap between them is measured against their average, so swapping A and B gives the same answer.

Try:

Answer

Enter your numbers or pick an example — the answer and the steps appear here instantly.

What you get

  • The formula, filled in

    |A − B| ÷ ((A + B) / 2) × 100, with your own numbers substituted at each stage of the outline.

  • Symmetric by design

    40 vs 60 and 60 vs 40 both give 40%, because neither value is treated as the starting point.

  • Exact, then displayed

    Fractions stay exact throughout, computed in your browser for free. A percentage with an endless decimal is rounded for display, marked ≈ and tagged Rounded.

How to compare two values

  1. Enter value A

    Type the first measurement, price or score. Decimals, fractions and decimal commas are fine.

  2. Enter value B

    Add the second value. Which one you call A and which B has no effect on the result.

  3. Calculate

    See the absolute difference, the average of the two and the percentage difference, then copy whichever figure you need.

  4. Ask why

    Pressing “Explain step by step” gets you a prose explanation from the AI Math Solver. It is a study aid that can contain errors, so hold it up against the numbered steps.

Percent change vs percentage difference vs percentage points

Percentage difference compares two values that have equal standing, like two lab measurements or the same product in two stores. For 40 and 60, the gap is |40 − 60| = 20, the average is (40 + 60) ÷ 2 = 50, and 20 ÷ 50 × 100 = 40%.

Percent change is for a before-and-after situation and divides by the starting value. From 40 to 60 is +50%, while from 60 to 40 is about −33.33%. The same pair of numbers gives three different answers depending on the question, and the percentage difference of 40% sits between the two changes.

Percentage points describe the gap between two percentages by plain subtraction. If one class averaged 40% on a test and another 60%, they are 20 percentage points apart, while their percentage difference is 40%. Say which measure you mean whenever you report a result.

One caution: the average in the denominator makes the formula unreliable when A and B have opposite signs or nearly cancel out. With 5 and −5 the average is 0, and there is no defined answer.

Frequently asked questions

No. The absolute value removes the sign of A − B, and the average is the same either way, so swapping the inputs never changes the result.

Choose percentage difference when neither value is a baseline, for example two quotes or two experimental readings. If one value clearly came first, percent change answers the question better.

Some sites call percent change “percentage difference” and divide by one of the values instead of their average. This page uses the average-based formula, so check which definition your textbook or teacher expects.

Yes. 10 and 50 differ by 40, their average is 30, and 40 ÷ 30 × 100 ≈ 133.33%. For two positive values the result always stays below 200%.

The comparison itself never costs anything and works without an account. AI explanations are included in the Pro plans* (*fair use: up to 300 runs a day in total across the writing, study and code tools); otherwise each one costs 2 credits, and a free preview of the first part is open to signed-out visitors.

That depends on your course. Many instructors are happy for you to check arithmetic with a calculator but limit AI-written explanations, so use the steps to learn and to confirm your own figures.

Tools for comparing data

Compare two values fairly

Get the percentage difference measured against the average, with every step written out.

Compare values
  • Order-independent result
  • Average and gap shown
  • Exact fractions inside