Percent Increase Calculator (Percent Change Calculator)

Percent increase measures how much a value grows relative to where it started. The key idea is that percent change always compares to the original value, not the new one. If you move from 80 to 100, you increased by 20, and that 20 is compared to 80. That is why the percent increase is 25%.

A percent increase is useful for prices, salaries, production outputs, conversion rates, and any situation where you want a relative comparison. It answers the question: How much larger is the new value compared to the original?

Percent decrease is the same calculation, but the change is negative because the new value is smaller than the original. The calculator labels the result as a decrease to avoid confusion. For example, dropping from 100 to 80 is a change of -20, and the percent change is -20%.

This is helpful for discounts, price drops, population declines, or decreases in revenue. The label makes it clear whether the number represents growth or decline.

The formula is simple and consistent:

• Percent change = ((new - original) / original) * 100

This formula produces a positive result for increases and a negative result for decreases. If the original value is zero, the percent change is undefined because division by zero is not allowed.

Using the wrong base

Percent change should always use the original value as the base. Using the new value changes the meaning and produces a different answer.

Confusing percent change with percentage points

Percent change is relative. Percentage points describe an absolute difference between two percentages. For example, going from 10% to 12% is a 2 percentage point increase, but a 20% percent change.

Reversing original and new

Swapping the values flips the direction. A change from 80 to 100 is a 25% increase. A change from 100 to 80 is a 20% decrease. The tool expects the original value first and the new value second.

1. Price increase from 80 to 100

• Change: +20
• Percent increase: 25%

2. Discount from 100 to 80

• Change: -20
• Percent decrease: 20%

3. Salary raise

• Original: 50,000
• New: 55,000
• Change: +5,000
• Percent increase: 10%

4. Stock price example

• Original: 25
• New: 30
• Change: +5
• Percent increase: 20%

5. Population growth

• Original: 2,000
• New: 2,200
• Change: +200
• Percent increase: 10%

6. Negative growth

• Original: 1,500
• New: 1,200
• Change: -300
• Percent decrease: 20%

7. Original value is zero

• Original: 0
• New: 25
• Percent change: undefined

The calculator shows a clear message instead of returning a misleading percent.

8. Reversing direction example

• From 100 to 80 = 20% decrease
• From 80 to 100 = 25% increase

9. +20% then -20% is not symmetric

• Start: 100
• After +20%: 120
• After -20%: 96

10. Multi-step growth

• Start: 1,000
• After +10%: 1,100
• After +10% again: 1,210

Percent change compounds when applied in steps.

Percent change compares the difference between two values to the original value. The formula is ((new - original) / original) * 100. This shows relative change rather than absolute change.

Use this tool when you need to express change as a percent, such as price increases, growth rates, or performance deltas.