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Percentage Increase Calculator

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Enter an old value and a new value to find the percentage increase or decrease between them.

Percentage Increase Calculator

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Percentage increase
50%
This measures directional change from a starting value. If you need a symmetric comparison instead, see the Percentage Difference Calculator below.

The formula

Percentage change = ((New value - Old value) / Old value) x 100 Positive result = increase - Negative result = decrease
Example

Old value 50, new value 75: (75-50)/50 x 100 = +50% increase. Old value 100, new value 80: (80-100)/100 x 100 = -20% decrease.

Step-by-step guide

  1. Enter the old (starting) value and the new (ending) value.
  2. Read the result - a positive percentage means an increase, negative means a decrease.

Percentage increase vs. percentage difference

These sound similar but answer different questions. Percentage increase/decrease is directional - it treats one number as the "before" and the other as the "after," and the order you enter them in matters (50 to 75 is a +50% increase, but 75 to 50 is a -33.3% decrease, not the reverse of +50%). Percentage difference, by contrast, is symmetric - it treats both numbers as simple values being compared with no "before" or "after," so the order doesn't matter. If you're tracking a change over time (like a price, a measurement, or a score), you want percentage increase/decrease. If you're just comparing two values with no time-based relationship, percentage difference is the more appropriate tool.

Common mistakes

Assuming a decrease and increase of the same size cancel out - a 50% increase followed by a 50% decrease does NOT return you to the original value, since each percentage applies to a different base number.
Swapping old and new values by mistake - since this calculation is directional, entering the values in the wrong order flips a genuine increase into what looks like a decrease.

Frequently asked questions

Why does a 50% increase then a 50% decrease not return to the original number?

Because each percentage is calculated from a different base. $100 increased by 50% becomes $150. But $150 decreased by 50% becomes $75, not back to $100 - the second percentage was calculated from the larger number.

What's the difference between this and a percentage difference calculator?

This calculator is directional (order matters, tracks change from a starting point over time). A percentage difference calculator is symmetric (order doesn't matter, just compares two values against each other).

Can the old value be zero?

No - percentage change from zero is mathematically undefined, since you'd be dividing by zero. Any increase from a starting point of zero is technically an infinite percentage increase.

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