Percentage Change Calculator

What is Percentage Change?

Percentage change represents the degree of change over time. It is widely used in finance to represent the price change of a security (like a stock or cryptocurrency). It can also be used to track changes in website traffic, business revenue, or personal test scores.

When the new value is larger than the original value, the result is a percentage increase. When the new value is smaller, it results in a percentage decrease.

The Percentage Change Formula

If you want to calculate percentage change manually, the mathematical formula is straightforward. You subtract the original value from the new value, divide the result by the absolute value of the original value, and multiply by 100.

Percentage Change =
[ (New Value – Old Value) / |Old Value| ] × 100

Note: We use the absolute value `|Old Value|` in the denominator to ensure the math works correctly even if the starting number is negative.

Example 1: Calculating a Percentage Increase

Imagine you bought a stock at $50 (Original Value) and the price went up to $75 (New Value). What is the percentage change?

Subtract the old value from the new value: 75 - 50 = 25
Divide the result by the old value: 25 / 50 = 0.5
Multiply by 100: 0.5 × 100 = 50%

The result is positive, meaning you had a 50% Increase.

Example 2: Calculating a Percentage Decrease

Now, let’s say a t-shirt originally cost $40, but it is on sale for $30. What is the discount percentage?

Subtract the old value from the new value: 30 - 40 = -10
Divide the result by the old value: -10 / 40 = -0.25
Multiply by 100: -0.25 × 100 = -25%

The result is negative, indicating a 25% Decrease (or a 25% discount).

Percentage Change vs. Percentage Difference

A very common mistake is confusing “Change” with “Difference”.

Percentage Change: Used when tracking a single item over time. There is a distinct “Old” value and “New” value. (Example: Your salary increased from $50k to $60k).
Percentage Difference: Used when comparing two different items at the same time where neither is the clear “original”. (Example: Comparing the height of Tree A to Tree B). For this, use our Percentage Difference Calculator.

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Frequently Asked Questions

How to calculate percentage change between two numbers?

To calculate the percentage change, subtract the old value from the new value. Divide that difference by the absolute value of the old value. Finally, multiply the result by 100. Formula: ((New Value – Old Value) / |Old Value|) × 100.

What is the difference between percentage change and percentage difference?

Percentage change tracks the growth or reduction of a single variable over time (e.g., a stock price from yesterday to today). Percentage difference compares two different things at the same time (e.g., the height of two different buildings) relative to their average.

Can a percentage change be negative?

Yes. If the new value is smaller than the old value, the calculation will result in a negative number, which represents a percentage decrease.

Calculate Change