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Percentage Change Calculator
This free percentage change calculator finds how much a value moved between two numbers, expressed as a percentage. Enter the old and new values to get the signed percent change, a clear increase or decrease label, and the absolute change amount. It handles price changes, growth rates and any before-and-after comparison.
How to use
- Enter the old (starting) value.
- Enter the new (final) value.
- Click Calculate to see the signed percent change.
- Read the increase or decrease label for the direction.
Worked example
A stock rises from $50 to $75. What is the percentage change?
Subtract: 75 - 50 = 25. Divide by the old value: 25 / 50 = 0.5. Multiply by 100: 0.5 x 100 = 50%. The stock shows a +50% change, labeled as a 50% increase.
If it had fallen from $80 to $60 instead: (60 - 80) / 80 x 100 = -25%, a 25% decrease.
When to use percent change versus percent difference
Use percent change when there is a clear before and after: prices, salaries, test scores over time, year-over-year growth. The old value is the base.
Use percent difference when comparing two things with no time order, like two products' prices. There the denominator is the average of both values, so the answer is the same whichever you list first.
Frequently asked questions
What is the percentage change formula?
Subtract the old value from the new value, divide by the absolute value of the old value, and multiply by 100: (new - old) / |old| x 100. From 50 to 75: (75 - 50) / 50 x 100 = 50%.
What does a positive or negative result mean?
Positive means the value increased; negative means it decreased. The calculator labels the direction for you, so +25% reads as a 25% increase and -25% reads as a 25% decrease.
Why divide by the absolute value of the old number?
The absolute value keeps the sign of the answer meaningful when the old value is negative. Without it, moves involving negative numbers would report backwards.
What if the old value is zero?
Percentage change is undefined when the old value is zero, since division by zero has no answer. The calculator will prompt you to enter a non-zero starting value.
Can I use negative numbers?
Yes. The formula works with negatives thanks to the absolute value in the denominator. Just read the increase or decrease label to interpret the direction correctly.
What is the difference between percent change and percent difference?
Percent change is directional and anchored to the old value, which is what you want for growth or decline. Percent difference divides by the average of the two numbers and has no direction, which suits neutral comparisons.
Does it work with decimals?
Yes, decimals work fine. Currency, measurements and statistics with decimal places all calculate correctly.