Percentage Change Calculator

Find the percent increase or decrease between two values.

Percentage change (%) 25

Absolute difference 20

Formula: change = (new − old) ÷ |old| × 100

Step-by-step with your numbers:

1. Values used:

2. Original value = 80

3. New value = 100

5. Percentage change = 25%

6. Absolute difference = 20

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Measure how much a value has gone up or down in percentage terms.

The math behind it

change = (new − old) ÷ |old| × 100. A positive result is an increase, a negative one is a decrease.

From 80 to 100 → (100 − 80) ÷ 80 × 100 = +25%.

Increase then same decrease isn't zero — why?

Because the base changes: +50% then −50% leaves you at 75% of the original, not 100%.