Percentage Change Calculator (Increase / Decrease)
Measure how much something grew or shrank in percentage terms — prices, salaries, followers, revenue, weight. Enter the old and new values and get the percentage change, its direction, and the absolute difference.
How to use this calculator
- Enter the original value — the starting point you're measuring from.
- Enter the new value.
- Press Calculate to see the percentage change, its direction, and the multiplication factor.
- Note the reverse row — undoing a change needs a different percentage than the change itself.
Formula used
The divisor is always the original value — the most common mistake is dividing by the new value. A positive result is an increase, negative a decrease. The multiplication factor (New ÷ Old) is often more intuitive for large changes: ×2 = +100%.
Example calculation
Salary raised from 2,500 to 3,100:
(3,100 − 2,500) ÷ 2,500 × 100 = 24% increase. The factor is ×1.24. To fall back to 2,500 from 3,100 would take a 19.35% decrease — not 24%, because the base changed.
Percentage change, done right
Percentage change expresses a difference relative to where you started, which makes changes comparable across scales: a 600 raise means a lot at 2,500/month and little at 25,000. The critical rule is that the original value is the base — always.
Two traps catch nearly everyone. First, asymmetry: a 20% drop followed by a 20% rise doesn't return to the start (100 → 80 → 96). Second, percentage points vs percent: an interest rate moving from 4% to 5% rose one percentage point but 25 percent. Being precise about these is what separates clear analysis from misleading headlines.
Why use this calculator?
- Measure raises, price hikes, growth metrics and losses on a comparable scale.
- See the reverse percentage — what it takes to undo a change — which intuition gets wrong.
- Avoid the classic wrong-base error that inflates or understates changes.
Frequently asked questions
How do I calculate percentage increase?
Subtract the original from the new value, divide by the original, multiply by 100. From 200 to 250: (250 − 200) ÷ 200 × 100 = 25% increase.
How do I calculate percentage decrease?
Same formula — the result just comes out negative. From 250 to 200: (200 − 250) ÷ 250 × 100 = −20%, i.e. a 20% decrease. Note it's not 25%: the base is different.
What is the difference between percentage change and percentage points?
Percentage points compare two percentages by subtraction (4% → 6% is +2 points). Percentage change compares them relatively (4% → 6% is a 50% increase). News headlines regularly blur the two — now you won't.
Why can't I calculate percentage change from zero?
The formula divides by the original value, and division by zero is undefined. Any growth from zero is infinite in percentage terms — report the absolute change instead.