Find the percentage change between two numbers instantly — with the formula and working shown
The percentage change formula is: ((Final Value − Initial Value) ÷ Initial Value) × 100. Going from 80 to 100 works out as ((100 − 80) ÷ 80) × 100 = 25% increase. Going from 100 down to 80 gives ((80 − 100) ÷ 100) × 100 = −20%, a 20% decrease. Notice the two answers are different even though the numbers are the same — percentage change is always measured relative to the starting value, which is the most common mistake when doing it by hand.
Enter your initial and final values above and the calculator shows the percentage change, direction (increase or decrease), the absolute difference and the full working so you can copy it into a report or homework answer. It handles decimals and negative numbers, and works for anything: salary hikes, price changes, sales growth, weight loss, rent increases, stock returns or year-over-year business comparisons.
These are often confused. If an interest rate moves from 10% to 15%, it rose by 5 percentage points, but the percentage increase is 50% (because 5 is half of the starting 10). News reports and financial documents use both — knowing the difference stops you misreading a claim. As with all our tools, the math runs entirely in your browser and nothing you type is uploaded or saved.