Percentage Change Calculator
Calculate the percentage increase or decrease between two values. Enter an original and new value — the result shows whether it's an increase or decrease, with full working.
Percentage increase or decrease
Enter the original (old) value and the new value. A positive result is an increase; a negative result is a decrease.
Find the new value after a percentage change
Enter a starting value and a percentage change to find the resulting value.
How to calculate percentage change
The formula for percentage change is: ((New − Old) ÷ Old) × 100. A positive result means an increase; a negative result means a decrease.
Worked example: price increase from $80 to $100
((100 − 80) ÷ 80) × 100 = (20 ÷ 80) × 100 = 0.25 × 100 = 25% increase.
Worked example: price decrease from $200 to $150
((150 − 200) ÷ 200) × 100 = (−50 ÷ 200) × 100 = −0.25 × 100 = −25% (a 25% decrease).
Percentage change vs percentage points
These are frequently confused. If an interest rate rises from 2% to 3%, that is a 1 percentage point increase — but a 50% relative percentage change (because 1 is 50% of 2). Percentage points measure the absolute arithmetic difference. Percentage change measures the relative shift from the original value.
Common uses
Salary raises: if you earn $55,000 and get a raise to $57,750, that is a ((57,750 − 55,000) ÷ 55,000) × 100 = 5% raise. Stock performance: if a share goes from $120 to $96, that is a 20% decline. Inflation: if a basket of goods costs $400 one year and $418 the next, that is a 4.5% inflation rate for that basket.
Frequently asked questions
Formula: ((New − Old) ÷ Old) × 100. From $80 to $100: ((100 − 80) ÷ 80) × 100 = 25% increase.
Use the same formula. From 200 to 150: ((150 − 200) ÷ 200) × 100 = −25%. The negative sign shows it is a decrease.
$250 × 1.10 = $275. The new value after a 10% increase is $275.
If a pass rate goes from 60% to 75%, that is a 15 percentage point increase, but a 25% relative change (15 ÷ 60 × 100 = 25%). Percentage points are the arithmetic difference; percentage change is the relative difference from the original.
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