Percentage Change Calculator

Step 1: Enter the original (old) value in the first field. This is the starting number — the baseline you are comparing from.

Step 2: Enter the new value in the second field. This is the number you are comparing to.

Step 3: Click Calculate. The result shows the percentage change (increase or decrease) along with the absolute difference between the two numbers.

Percentage change measures how much a value has increased or decreased relative to its original amount. It answers the question: "By what proportion did this value change?"

Percentage increase means the new value is larger than the original. If a stock price goes from $100 to $125, it increased by 25%. Percentage decrease means the new value is smaller. If the price drops from $100 to $80, it decreased by 20%.

Why percentage change matters more than absolute change: A $10 raise means very different things depending on context. If you earned $100/week, a $10 raise is a 10% increase. If you earned $10,000/week, the same $10 is only a 0.1% increase. Percentage change normalizes the comparison to the starting value.

Common applications: Stock market returns, salary increases, population growth, price inflation, weight loss progress, sales performance, year-over-year business metrics, and scientific measurements.

Percentage change vs percentage points: If interest rates go from 5% to 7%, the change is 2 percentage points but a 40% increase. These are different measures — percentage change is relative to the starting value, while percentage points measure the absolute difference between two percentages.

Percentage Change = ((New Value − Original Value) / |Original Value|) × 100

The absolute value of the original is used in the denominator to ensure the formula works correctly with negative numbers.

Positive result = increase. Negative result = decrease.

Example 1: Original = $80, New = $100
Change = ((100 − 80) / 80) × 100 = (20/80) × 100 = 25% increase

Example 2: Original = $100, New = $75
Change = ((75 − 100) / 100) × 100 = (−25/100) × 100 = 25% decrease

Example 3: Original = $50, New = $150
Change = ((150 − 50) / 50) × 100 = (100/50) × 100 = 200% increase

Important: Percentage change is not symmetrical. A 50% increase from $100 gives $150. But a 50% decrease from $150 gives $75, not back to $100. This asymmetry is why tracking percentage change in both directions matters.

Example 1: Salary Increase
Your salary went from $65,000 to $72,000. Enter 65000 as old value, 72000 as new. Result: 10.77% increase. The $7,000 raise represents about a 10.8% increase.

Example 2: Price Drop
A laptop was $1,200 and is now on sale for $899. Enter 1200 and 899. Result: 25.08% decrease. You are saving about 25% off the original price.

Example 3: Investment Return
You invested $5,000 and your portfolio is now worth $13,500. Enter 5000 and 13500. Result: 170% increase. Your investment grew to 2.7 times its original value.

Always enter the original value first. The order matters. Swapping the values gives a different percentage because the base changes. $80 to $100 is a 25% increase, but $100 to $80 is a 20% decrease.

Percentage change can exceed 100%. A 200% increase means the value tripled (original + 2× original). A 500% increase means it became 6 times the original. There is no upper limit.

Cannot calculate from zero. If the original value is 0, percentage change is undefined because you would be dividing by zero. The calculator shows N/A in this case.

Use for year-over-year comparisons. Revenue went from $500K to $750K? That is a 50% increase. Much more meaningful than just saying "it went up by $250K."

Percentage decreases max out at 100%. A value can only decrease by at most 100% (to zero). It cannot decrease by more than 100% unless we are talking about values going negative, which has a different interpretation.