Free percentage change calculator
Find the percentage increase or decrease between two numbers, plus the absolute difference. The everyday "how much did it move?" calculation. Runs in your browser.
How it works
No black box — here's exactly what the calculator does.
It subtracts the original value from the new value. A positive result means the figure went up; a negative result means it went down.
It divides that change by the original value, which expresses the move relative to where you started.
Multiplying the ratio by 100 turns it into a percentage you can read and compare at a glance.
If the original value is zero the percentage is undefined — you can't divide by zero. And a big percentage on a tiny base is mostly noise, so always check the absolute change too.
FAQ
How do you calculate percentage change?
Subtract the original value from the new value, divide by the original value, then multiply by 100. A positive result is an increase and a negative result is a decrease.
What is the percentage change formula?
Percentage change = ((new value - original value) / original value) x 100.
Why is my percentage change showing as undefined?
Because the original value is zero. Dividing by zero is undefined, so there is no meaningful percentage change from a base of zero - look at the absolute change instead.
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