How to Calculate Percentage Increase (With Real Examples)
If you've ever gotten a raise at work, watched a stock price move, or noticed your grocery bill creeping up, you've run into percentage increase without necessarily knowing the formula behind it. Once you understand it, you'll never need a calculator for the basic cases — though for anything more complex, our Percentage Calculator handles it instantly.
The Basic Formula
Percentage increase is calculated by taking the difference between the new value and the original value, dividing that difference by the original value, and multiplying by 100. In simple terms: ((New Value - Original Value) / Original Value) × 100.
Example 1: A Salary Raise
Suppose your salary goes from $50,000 to $56,000. The difference is $6,000. Divide that by the original salary ($50,000), which gives 0.12. Multiply by 100, and you get a 12% increase. That single number tells you far more than the raw dollar amount alone — it lets you compare raises across different salary levels fairly.
Example 2: A Price Increase
Say a product you buy regularly goes from $4.00 to $4.50. The difference is $0.50. Divide by the original price ($4.00), giving 0.125. Multiply by 100, and the price has increased by 12.5%. Even small dollar changes can represent meaningful percentage jumps when the original price is low.
What About Percentage Decrease?
The formula works the same way for decreases — you'll just end up with a negative result, which represents the percentage drop. For example, if a $100 item drops to $80, the difference is -$20, divided by $100 gives -0.20, or a 20% decrease.
A Common Mistake to Avoid
The most frequent error is dividing by the new value instead of the original value. Always divide the difference by the starting number, not the ending one — this is what most people get backwards, and it produces a noticeably different (and incorrect) percentage.
When This Matters in Real Life
Percentage increase calculations show up constantly: comparing year-over-year business growth, understanding inflation on everyday goods, evaluating investment returns, or negotiating a raise with actual data instead of a gut feeling. Once you're comfortable with the formula, these numbers stop feeling abstract and start being genuinely useful decision-making tools.
Try It Yourself
Rather than doing the math by hand every time, you can plug your numbers into our free Percentage Calculator, which includes a dedicated tab for percentage increase and decrease calculations.