Percentage Change Calculator
Enter the starting value and the new value to get the percentage change, the difference and its direction (up, down or none).
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Formula
change % = (new − old) ÷ |old| × 100. A positive result is an increase, a negative one a decrease. The old value cannot be zero.
Worked example
From 80 to 100: (100 − 80) ÷ 80 × 100 = +25%, an increase of 20. From 100 to 80: (80 − 100) ÷ 100 × 100 = −20%. From 3 to 10: 7 ÷ 3 × 100 = 233.33%.
Frequently asked questions
How do I calculate percentage change?
Subtract the old value from the new value, divide by the old value and multiply by 100. From 80 to 100 that is 20 ÷ 80 × 100 = 25% increase.
Why is a rise and fall of the same size not the same percentage?
The percentage is always measured against the starting value. Going from 80 to 100 is +25%, but going back from 100 to 80 is -20%.
What if the old value is zero?
Percentage change from zero is undefined because you cannot divide by zero, so the calculator shows an error. Use the absolute difference instead.
How are negative starting values handled?
The calculator divides by the absolute value of the old value, so a rise is always positive. From -50 to -25 the change is 25 ÷ 50 = +50%.