Percentage Change Calculator
Percentage change = (new value − old value) ÷ old value × 100. A positive result is a percentage increase; a negative result is a percentage decrease.
Last updated 2026-08-14
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quizExample
How this calculator works, with real numbers (no JavaScript needed):
Inputs
- Original value
- 80
- New value
- 100
Results
- Percentage change
- 25%
- Absolute change
- 20
functionsThe formula
Percentage change tells you how much a value moved, as a proportion of where it started — the standard way to report growth, inflation, stock moves and scores.
The formula
Percentage change = (new value − original value) ÷ original value × 100
Worked examples
From 80 to 100:
(100 − 80) ÷ 80 × 100 = 20 ÷ 80 × 100 = +25%
So 80 → 100 is a 25% increase.
From 100 to 80:
(80 − 100) ÷ 100 × 100 = −20 ÷ 100 × 100 = −20%
So 100 → 80 is a 20% decrease.
Notice the asymmetry: a 25% rise from 80 lands on 100, but it takes a 25% drop from 100 to fall back to 75. Percentages work on the current value, so increases and decreases don't cancel symmetrically.
Why the base matters
Percentage change is always relative to the starting value. A ₹10 rise from ₹100 is +10%, but the same ₹10 rise from ₹1,000 is just +1%. Always state the base when quoting a percentage change — "profits grew 25%" means little without "from what?".
Uses
- Finance — returns on investments, price moves, inflation
- Business — sales growth, budget variance
- Everyday — weight changes, grades, cricket score improvements
Need to add or subtract a percentage to/from a number instead? Use the percentage increase or percentage decrease calculators.
helpFrequently asked questions
question_markHow do I calculate percentage change?
Subtract the original value from the new value, divide by the original value, and multiply by 100. A positive result is an increase; a negative result is a decrease.
question_markWhat is the percentage increase from 80 to 100?
((100 − 80) ÷ 80) × 100 = 25%. So 80 → 100 is a 25% increase.
question_markIs a 20% decrease the reverse of a 25% increase?
Not exactly. A 25% increase from 80 gives 100, but a 20% decrease from 100 gives 80 — the two do reverse each other here only because the percentages are computed from different bases.