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25%
900 is a 25% decrease from 1,200
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The percent change formula
Percentage change = (new value − original value) ÷ original value × 100
How to calculate a percent change
- 1.Subtract the original value from the new value. A negative answer here means it fell.
- 2.Divide by the original value.
- 3.Multiply by 100. A positive result is an increase and a negative result is a decrease.
Worked example
Visitors went from 1,200 one month to 900 the next. What is the percentage change?
- 900 − 1,200 = −300
- −300 ÷ 1,200 = −0.25
- −0.25 × 100 = −25%
A 25% decrease, shown as −25% because the figure fell.
Percent change is not percentage difference
Percent change has a direction and is measured against the value you started from, so swapping the two numbers changes the answer. Percentage difference compares two values where neither is the baseline. Use change when one value came first.
Common questions
How do you calculate percent change?
Take the new value minus the original, divide by the original, and multiply by 100. A negative answer means a decrease.
Does the order of the numbers matter?
Yes. Percent change measures against the value you started from, so putting them the other way round gives a different figure. Percentage difference is the one that ignores order.
What if the original value is zero?
Percent change cannot be worked out from zero, because the sum would divide by zero. Any rise from nothing is undefined rather than infinite.
Other percentage calculations
How it works
The percent change formula
Percentage change = (new value − original value) ÷ original value × 100
How to calculate a percent change
Subtract the original value from the new value. A negative answer here means it fell. Divide by the original value. Multiply by 100. A positive result is an increase and a negative result is a decrease.
Percent change is not percentage difference
Percent change has a direction and is measured against the value you started from, so swapping the two numbers changes the answer. Percentage difference compares two values where neither is the baseline. Use change when one value came first.