Percentage Change Calculator

📐 Percentage Change Formula

Percentage change measures the difference between a new value and an original value relative to the size of the original value.

For ordinary positive values, |Original value| is simply the original value. The absolute-value notation becomes relevant when signed values are entered.

↑ Percentage Increase Example

Suppose a value rises from 100 to 125. First find the difference:

Then compare that difference with the original value:

The value therefore increased by 25%.

↓ Percentage Decrease Example

If a value falls from 200 to 150, the difference is −50:

The negative sign indicates direction, so this is a 25% decrease.

🔎 How to Read Your Result

The calculator provides more than the percentage alone. It also displays the absolute difference, whether the value increased or decreased, and the ratio of the new value to the original value.

± Absolute Difference vs Percentage Change

The absolute difference tells you how many units were added or removed. Percentage change tells you how large that difference is relative to the original value.

For example, a rise from 100 to 125 and a rise from 1,000 to 1,025 both have an absolute increase of 25. However, the first is a 25% increase while the second is only a 2.5% increase.

× Understanding the New-to-Original Ratio

Dividing the new value by the original value provides another way to understand the comparison. A ratio of 1.25 means the new value is 1.25 times the original value. A ratio of 0.75 means the new value is three-quarters of the original.

💡 Percentage Change vs Percentage Points

These two terms describe different calculations. This distinction matters when the values being compared are themselves percentages.

Suppose a rate changes from 20% to 25%.

So the rate increased by 5 percentage points, while its relative percentage increase was 25%. These descriptions are not interchangeable.

0 What Happens When the Original Value Is Zero?

Standard percentage change divides the difference by the original value. When the original value is zero, that calculation would require division by zero.

For that reason, this calculator does not display a finite percentage change when the original value is zero. You can still describe the absolute change—for example, “the value increased from 0 to 50”—without assigning a standard percentage increase.

− What About Negative Starting Values?

Percentage change is straightforward when comparing ordinary positive quantities. Signed values require more care because the meaning depends on what the numbers represent.

For example, moving from −100 to −50 is numerically an upward movement of 50 units. Using the magnitude of the starting value gives a 50% increase in the numerical value. However, whether that should be described as an improvement, reduction in loss, or something else depends on the context.

📊 Common Percentage Change Examples

🛒 Prices and Costs

You can compare an earlier price with a later price to see the relative increase or decrease. If an item rises from 80 to 100, the percentage increase is 25%.

📈 Business Values

Percentage change can compare quantities such as revenue, orders, units sold or costs across two periods. The two values should represent comparable measurements and use the same units.

🎓 Scores and Measurements

The calculation can also compare two measurements or scores. Remember that if the values are already percentages, you may need to distinguish relative percentage change from percentage-point change.

🧠 Percentage Change Is Not Always Symmetrical

A percentage increase followed by the same percentage decrease does not normally return a value to where it started.

For example, increase 100 by 20%:

Now decrease 120 by 20%:

The final value is 96, not 100. This happens because the second percentage is calculated from a different starting value.

Likewise, moving from 100 to 150 is a 50% increase, but returning from 150 to 100 is a 33.333% decrease. The denominator changes because percentage change is always measured relative to the starting value of that particular comparison.