Percentage Change Calculator - Increase & Decrease

Calculate percentage increase or decrease between two numbers with our free online percentage change calculator. Perfect for tracking growth, price changes, and performance metrics.

Original Value (From)

New Value (To)

Examples:

Understanding Percentage Change

Percentage change measures how much a value has increased or decreased relative to its original amount. It's one of the most practical math concepts you'll use daily - from tracking investment returns to comparing sale prices to understanding population growth.

What makes percentage change so useful is that it standardizes comparisons. A $10 increase means very different things for a $20 stock versus a $2000 laptop. Expressing changes as percentages puts everything on the same scale.

The Percentage Change Formula

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

The absolute value of the original value ensures the formula works correctly even when dealing with negative starting values. A positive result means an increase; negative means a decrease.

Percentage Increase

When the new value is larger than the original:

Original: 100, New: 150

((150 - 100) / 100) × 100% = 50%

Result: 50% increase

Percentage Decrease

When the new value is smaller than the original:

Original: 200, New: 150

((150 - 200) / 200) × 100% = -25%

Result: 25% decrease

Worked Examples

Example 1: Stock Price Increase

You bought shares at $45 each. Today they're worth $63. What's your percentage gain?

Original Value = $45

New Value = $63

Absolute Change = $63 - $45 = $18

Percentage Change = ($18 / $45) × 100% = 0.4 × 100% = 40%

Your investment grew by 40%

Example 2: Sale Discount

A jacket originally priced at $120 is now $84. What percentage discount is this?

Original Value = $120

New Value = $84

Absolute Change = $84 - $120 = -$36

Percentage Change = (-$36 / $120) × 100% = -0.3 × 100% = -30%

You're saving 30% off the original price

Example 3: Population Growth

A town had 8,500 residents in 2020 and 9,860 in 2024. What was the population growth rate?

Original Value = 8,500

New Value = 9,860

Absolute Change = 9,860 - 8,500 = 1,360

Percentage Change = (1,360 / 8,500) × 100% = 0.16 × 100% = 16%

The town grew by 16% over 4 years

Example 4: Weight Loss Journey

Starting at 220 lbs, someone reaches a goal weight of 187 lbs. What percentage of body weight did they lose?

Original Value = 220 lbs

New Value = 187 lbs

Absolute Change = 187 - 220 = -33 lbs

Percentage Change = (-33 / 220) × 100% = -0.15 × 100% = -15%

They lost 15% of their starting body weight

Quick Fact

The percent symbol (%) comes from the Latin "per centum," meaning "by the hundred." Ancient Romans used fractions based on 1/100 for calculations - Emperor Augustus levied a 1% tax on goods sold at auction. The modern % symbol evolved from 17th-century Italian merchants writing "pc" with a line through it, eventually becoming the two circles and slash we use today.

Frequently Asked Questions

Can percentage change be more than 100%?

Absolutely. If something doubles, that's a 100% increase. If it triples, that's a 200% increase. For example, going from $50 to $200 is a 300% increase because you've added three times the original amount.

What's the difference between percentage change and percentage point change?

Percentage change is relative (a ratio), while percentage points are absolute differences between percentages. If unemployment goes from 5% to 7%, that's a 2 percentage point increase, but a 40% percentage change ((7-5)/5 × 100%).

How do I calculate percentage change when the original value is negative?

Use the absolute value of the original in the denominator. If a company goes from -$10,000 loss to $5,000 profit: ((5000 - (-10000)) / |-10000|) × 100% = (15000 / 10000) × 100% = 150% improvement.

Why is my percentage decrease smaller than the percentage increase for the same absolute change?

Because the base (original value) is different. Going from 100 to 150 is a 50% increase. But going from 150 back to 100 is only a 33.3% decrease. The same $50 change represents different proportions of the starting values.

How is percentage change used in real life?

You'll find percentage change everywhere: investment returns (ROI), inflation rates, sales discounts, population growth, website traffic analytics, test score improvements, fitness progress tracking, and economic indicators like GDP growth.

What if the original value is zero?

Percentage change from zero is mathematically undefined (division by zero). In practice, if you go from 0 to any positive number, you might describe it as "infinite growth" or simply state the absolute change instead.

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