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Percentage Difference Calculator

Find the percent difference between two values (no "before" or "after" — order doesn't matter).

Percentage difference formulas

Percentage difference|a − b|(a + b) / 2 × 100
Compare: percent changenew − oldold × 100

Worked examples

  1. Two stores sell the same item for $40 and $60.

    1. |40 − 60|(40 + 60) / 2 × 100 = 2050 × 100

    Answer: 40%

  2. The same numbers as a percent change.

    1. 40 → 60: 20 ÷ 40 = +50%
    2. 60 → 40: −20 ÷ 60 ≈ −33.3%

    Answer: Use % difference when neither value is the "starting" one

Tips & common mistakes

  • Percentage difference is symmetric — swapping a and b gives the same answer.