Prices rise, salaries grow, scores improve — and the honest way to describe all of it is a percentage change. This free percentage increase calculator answers the two questions everyone actually asks. First: “from this number to that number, what is the percentage increase or decrease?” — enter a starting value and a new value and get the change, the difference and the direction. Second: “what is this value increased (or decreased) by X percent?” — enter the value and the percentage and get the exact result, which is the calculation behind pay rises, price markups, discounts and interest. Both tools update as you type, show their working so you can trust them, and handle the awkward cases (negative numbers, big drops, increases over 100%) without complaint. No sign-up, nothing uploaded — just the maths, done properly.
The formula for percentage change
Percentage change = (new value − old value) ÷ |old value| × 100. Going from 80 to 100: the difference is 20, divided by the starting 80 gives 0.25, times 100 is a 25% increase — the example loaded in the calculator above. The starting value is always the denominator, and that single fact explains the most common percentage mistake in everyday life: percentages are not symmetric. A price that rises 25% from 80 reaches 100, but to fall back from 100 to 80 it only needs a 20% decrease, because the same 20 is now divided by 100. Lose 50% of an investment and you need a 100% gain — not 50% — to get back to even.
Applying a percentage: markups, discounts, raises
The second tool multiplies a value by (1 + percentage ÷ 100). A 20% increase on 250 is 250 × 1.20 = 300. A decrease uses a negative percentage: −30% on 250 gives 250 × 0.70 = 175. This one formula covers a raise negotiation (what is my salary after a 7% increase?), retail (what is the sale price after 40% off?), tax questions (what is the total after 21% VAT is added?) and tipping. Note the VAT case carefully: adding 21% and later “removing 21%” do not cancel out, for the same denominator reason as above — to strip out 21% VAT from a gross price you divide by 1.21, you do not subtract 21%.
Percentage points are not percent
When the thing changing is itself a percentage, language matters. If an interest rate moves from 4% to 5%, that is an increase of one percentage point, but a 25% relative increase. News reports that mix these up are not always being careless — sometimes the bigger number just makes a better headline. The calculator above works in relative percent: feed it 4 and 5 and it correctly reports a 25% increase. If you are reading a claim about rates, scores or poll numbers, work out which of the two is meant before you react to the size of the change.
Frequently asked questions
How do I calculate a percentage increase?
Subtract the old value from the new one, divide the result by the old value, and multiply by 100. From 60 to 75: (75 − 60) ÷ 60 = 0.25, so a 25% increase.
Can a percentage increase be more than 100%?
Yes. Any time a value more than doubles it has increased by more than 100%: from 30 to 75 is a 150% increase. Decreases, by contrast, can never exceed 100% for a positive value — losing 100% means reaching zero.
What is the difference between this and a percentage difference calculator?
Percentage change compares a new value against a specific starting value (before vs after). Percentage difference compares two values symmetrically, dividing by their average, when neither is the “original.” Use this tool when there is a before and an after.
Why does the calculator refuse a starting value of 0?
Because the formula divides by the starting value, and division by zero is undefined: going from 0 to anything is not a percentage that exists. Pick any non-zero baseline instead.
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Versión en español: Calculadora de Aumento Porcentual — Cambio Porcentual entre Dos Números. You may also like: Salary to Hourly Calculator — Convert Annual Pay to an Hourly Rate · Average Calculator — Mean, Median, Mode & Range of Any Number Set.
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