This percent change calculator finds the percentage increase or decrease between two values — and also computes percent difference, the close cousin that confuses everyone, with the two clearly labeled.

Percent Change (from → to)–
Absolute Change–
Percent Difference (symmetric)–

Percent Change, Precisely

Percent change = (new − old) ÷ old × 100. The old value is the base — always — because the question is "relative to where we started." It partners with the general-purpose Percentage Calculator in our Math Calculators collection.

Worked Examples (Verified)

  • 80 → 100: (100−80)/80 = +25% increase
  • 100 → 80: (80−100)/100 = −20% — the mirror trip is a different percentage! Going up 25% and then down 20% returns you to exactly 80, which is why a 50% loss needs a 100% gain to recover
  • Percent difference between 80 and 100: 20 ÷ their average (90) = 22.22% — direction-free, used when neither value is "the original" (comparing two measurements, two cities' prices, two labs' results)

Change vs. Difference vs. Percentage Points

  • Percent change — ordered, has a base and a direction (prices rose 25% from last year).
  • Percent difference — unordered, symmetric, divides by the average (the two thermometers differ by 2%).
  • Percentage points — the raw subtraction of two percentages: a rate moving from 4% to 5% rose by 1 percentage point, which is a 25% increase in the rate. Headlines mixing these two up are a genre unto themselves.

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Frequently Asked Questions

How do I calculate percent change?

Subtract old from new, divide by the old value, multiply by 100. (100 − 80) ÷ 80 × 100 = +25%. Sign tells direction: positive increase, negative decrease.

What is the difference between percent change and percent difference?

Change divides by the original value and has a direction; difference divides by the average of the two values and is symmetric (80 ↔ 100 gives 22.22% either way). Use difference when there is no "before and after."

Why doesn't a 25% increase followed by a 25% decrease return to the start?

The bases differ: the increase acts on 80, the decrease on the larger 100 — 25% of 100 is 25, leaving 75, not 80. Undoing a +25% takes exactly −20%.

Can percent change exceed 100%?

Increases, yes, without limit (80 → 240 is +200%). Decreases of a positive quantity cap at −100% (reaching zero). Negative starting values make the formula's sign treacherous — interpret with care.

Percent increase from 4% to 5% interest — is that 1% or 25%?

Both, said correctly: +1 percentage point, which is a +25% relative increase. Precision about which one you mean prevents most arguments about statistics in the news.

Is this percent change calculator free?

Yes — free, instant, no sign-up.