Percentage Increase Calculator
Enter an old value and a new value — the percentage increase or decrease is worked out instantly, with the difference and the reverse change shown too.
How Percentage Increase Is Calculated
Every percentage change is a comparison against where you started. The formula has three steps: find the difference between the two values (new − old), divide that difference by the old value, and multiply by 100 to express the result as a percentage. Dividing by the old value is the step people most often get wrong — divide by the new value instead and you answer a different question entirely (that is the reverse change, which this page shows separately).
The sign carries the meaning. A positive result is an increase, a negative result is a decrease, and zero means the value did not move. Alongside the percentage, this calculator shows two supporting figures: the absolute difference, which is often the number that actually matters for money, and the multiplier (new ÷ old), which is how growth is expressed in investing — a multiplier of 1.25 and a 25% increase are the same fact in different clothes.
Worked Example: A Pay Rise from $50,000 to $54,000
- Difference: $54,000 − $50,000 = $4,000.
- Divide by the original salary: $4,000 ÷ $50,000 = 0.08.
- Multiply by 100: 0.08 × 100 = 8% — an 8% pay rise.
Run two price moves through the same steps to see the asymmetry that catches people out. A jacket rising from $80 to $100 is a 25% increase (20 ÷ 80). The same jacket falling back from $100 to $80 is only a 20% decrease (20 ÷ 100) — identical $20 steps, different percentages, because the starting point changed. That is why a store can advertise "25% off" a price it quietly raised by 25% first and still come out ahead: $80 → $100 → $75.
Percentage Change in Everyday Decisions
The pattern repeats anywhere two numbers are compared across time. Rent moving from $1,450 to $1,595 a month is a 10% increase (145 ÷ 1,450) — worth knowing before you sign, because a "small" $145 is a tenth of your housing budget. A savings rate growing from 3.0% to 4.5% sounds tiny but is a 50% increase in the interest you earn. And a portfolio that falls 50% needs a 100% increase just to break even, the harshest version of the base-effect above. For the neighbouring calculations, the Percentage Calculator covers "what is X% of Y" questions, and the Percent Off Calculator turns discount percentages into final prices.
Frequently Asked Questions
What is the formula for percentage increase?
Subtract the old value from the new value, divide the difference by the old value, then multiply by 100: (new − old) ÷ old × 100. A price moving from $80 to $100 gives (100 − 80) ÷ 80 × 100 = 25, a 25% increase. The calculator above runs exactly this formula and shows the difference and the multiplier alongside the percentage.
How do I calculate a percentage decrease?
With the same formula — the sign takes care of itself. If the new value is smaller, the difference is negative and the result is a decrease: a price falling from $50 to $40 gives (40 − 50) ÷ 50 × 100 = −20, a 20% decrease. This page labels the direction for you instead of making you interpret the minus sign.
What does a 100% increase mean?
A 100% increase means the value has doubled. The increase itself equals the whole original value, so the new total is twice the old one: 250 growing by 100% becomes 500. A 200% increase triples the value (250 → 750), and anything over 100% means the growth alone is bigger than what you started with.
What is the difference between a percentage increase and percentage points?
Percentage points measure the gap between two percentages directly; percentage increase measures the change relative to the starting percentage. An interest rate rising from 3% to 4% is up 1 percentage point, but as a percentage increase it is (4 − 3) ÷ 3 × 100 = 33.3% higher. News reports that mix the two up can make a change sound three times bigger — or smaller — than it is.
Why does a 25% increase followed by a 25% decrease not get me back to the start?
Because the second percentage is calculated on a different base. Start at $80: a 25% increase adds $20 and takes you to $100. A 25% decrease from $100 takes away $25, leaving $75 — not $80. To undo a 25% increase you need a 20% decrease, which is why this calculator also shows the exact reverse change needed to return to the original value.
Can the old value be zero?
No — percentage change from zero is undefined, because the formula divides by the old value and division by zero has no answer. Going from 0 sales to 50 sales is real growth, but it cannot be expressed as a percentage of nothing. This calculator tells you that instead of inventing a number; describe such a change in absolute terms instead.
Is this percentage increase calculator free?
Yes. It is completely free with no signup required, and it runs entirely in your browser — the numbers you enter are never uploaded, stored or shared.