How to Calculate Percentage Change

Percentage change is used to measure how much a value has increased or decreased compared with its original amount. It is commonly used in business, finance, education, economics, statistics, and everyday calculations.

For example, you can use it to compare a product’s price before and after a discount, measure monthly website traffic growth, calculate changes in expenses, or track revenue over time.

This calculator makes it easy to compare two values, find the percentage increase or decrease, and calculate the difference between them.

What Is Percentage Change?

Percentage change is the relative difference between an original value and a new value, expressed as a percentage of the original value.

A positive result generally represents an increase, while a negative result represents a decrease when the original value is positive. A result of zero means that the value has not changed.

For example, if a product’s price rises from $50 to $65, the value has increased by $15. The percentage change is 30%.

Percentage Change Formula

The standard formula is:

Percentage Change = ((New Value − Original Value) ÷ Original Value) × 100

To calculate it:

1. Subtract the original value from the new value.
2. Divide the result by the original value.
3. Multiply the result by 100 to convert it into a percentage.

Example of Percentage Increase

Suppose your monthly website visitors increase from 10,000 to 12,500.

• Original value: 10,000
• New value: 12,500
• Difference: 2,500

Percentage change = (2,500 ÷ 10,000) × 100 = 25%

Your website traffic increased by 25%.

Example of Percentage Decrease

Imagine a product’s price falls from $200 to $150.

• Original value: $200
• New value: $150
• Difference: −$50

Percentage change = (−50 ÷ 200) × 100 = −25%

The price decreased by 25%.

Percentage Change Examples

Original Value	New Value	Percentage Change
50	75	+50%
100	120	+20%
200	150	−25%
500	400	−20%
800	1,000	+25%
1,200	1,500	+25%
2,000	1,600	−20%

A positive sign indicates an increase, while a negative sign indicates a decrease for positive starting values.

Percentage Change vs. Percentage Difference

Although these terms are often used interchangeably, they have different mathematical meanings.

Percentage change uses the original value as its baseline. Percentage difference uses the average of the absolute values being compared as its denominator.

For example, when comparing 80 and 100:

• Percentage change from 80 to 100: 25%
• Percentage difference between 80 and 100: 22.22%

Use percentage change when one value is the original and the other is the updated value. Use percentage difference when comparing two values without assigning one as the starting point.

How to Calculate Percentage Increase

To calculate a percentage increase, subtract the original value from the new value, divide by the original value, and multiply by 100.

For example, if your monthly income increases from $2,500 to $3,000:

Percentage increase = ((3,000 − 2,500) ÷ 2,500) × 100 = 20%

Your income increased by 20%.

How to Calculate Percentage Decrease

To calculate a percentage decrease, subtract the new value from the original value, divide by the original value, and multiply by 100. This gives the decrease as a positive percentage.

For example, if a product’s price drops from $80 to $60:

Percentage decrease = ((80 − 60) ÷ 80) × 100 = 25%

The price decreased by 25%.

How to Calculate a New Value After a Percentage Change

If you know the original value and the percentage change, you can calculate the resulting value.

New Value = Original Value × (1 + Percentage Change ÷ 100)

For example, if an amount of $400 increases by 15%:

New value = 400 × (1 + 15 ÷ 100) = $460

For a 10% decrease:

New value = 400 × (1 − 10 ÷ 100) = $360

You can use the reverse calculator above to perform these calculations automatically.

Where Is Percentage Change Used?

Percentage change is useful in many situations, including:

• Business: Comparing revenue, expenses, sales, and profit over time.
• Finance: Measuring price movements, returns, and changes in account balances.
• Education: Comparing test scores, assessment results, and performance.
• Marketing: Tracking website visitors, conversions, advertising costs, and campaign results.
• Retail: Calculating price increases, discounts, and changes in product costs.
• Economics: Describing changes in inflation measures, employment figures, and other indicators.

When comparing values over time, make sure the periods and units are comparable.

Can Percentage Change Be Calculated From Zero?

The standard percentage change formula requires a non-zero original value because it divides by that value.

If the original value is zero and the new value is positive, the absolute change can still be calculated, but the conventional percentage change is undefined.

For example, going from 0 to 50 represents an absolute increase of 50, but it does not have a mathematically defined percentage change.

Frequently Asked Questions

What is the formula for percentage change?

Subtract the original value from the new value, divide the difference by the original value, and multiply by 100.

How do I calculate percentage increase between two numbers?

Subtract the original number from the new number, divide the result by the original number, and multiply by 100. A positive result indicates an increase when the original value is positive.

How do I calculate percentage decrease?

Subtract the new value from the original value, divide the difference by the original value, and multiply by 100. This expresses the decrease as a positive percentage when the original value is positive and the new value is lower.

Can percentage change be negative?

Yes. A negative percentage change generally represents a decrease when the starting value is positive. When the starting value is negative, the sign follows the mathematical formula and may not match the everyday interpretation of an increase or decrease.

What is the difference between percentage change and percentage difference?

Percentage change compares a new value with a specific original value. Percentage difference compares two values relative to the average of their absolute values, without assigning one as the baseline.

What happens if the original value is zero?

Percentage change is undefined when the original value is zero. You can still calculate the absolute difference between the values.

Can percentage change be more than 100%?

Yes. If a value increases from 20 to 50, the percentage change is 150%. A decrease from a positive starting value cannot exceed 100% if the ending value is also non-negative.

Does the calculator support money values?

Yes. You can format monetary values using USD, INR, EUR, GBP, CAD, or AUD. The currency setting only changes how amounts are displayed; it does not perform currency conversion.

Note: Results are mathematical comparisons based on the values entered. For negative starting values, the conventional formula can produce signs that need careful interpretation.