One tool for both increases and decreases — the sign tells you which.
Percentage Change
-15%
The value decreased.
Percentage change is the general-purpose version of the increase/decrease calculators — instead of assuming which direction the number moved, it works out the change and tells you with a plus or minus sign. A positive result means the value went up; a negative result means it went down.
This is useful when you are comparing values in a spreadsheet or dataset and do not know in advance whether each pair went up or down — one formula handles both cases correctly.
Formula
Percentage Change = ((New Value − Old Value) ÷ Old Value) × 100
A positive result is an increase; a negative result is a decrease.
Worked Example
Worked example
Reading the sign correctly
Do not drop the minus sign when reporting a decrease — "−15% change" and "15% change" mean opposite things. If you specifically want a clean positive number for a known decrease, the dedicated Percentage Decrease Calculator does that automatically.
When the old value is zero
Percentage change is undefined when the old (starting) value is zero, because you cannot divide by zero — going from 0 to any positive number is technically an infinite percentage increase, so it is usually better described in absolute terms in that specific case.
Frequently Asked Questions
What is the difference between percentage change and percentage increase?
Percentage increase always assumes the value went up and gives a positive result. Percentage change works for both directions and uses the sign (+/−) to show which way the value moved.
Why is my percentage change negative?
A negative percentage change means the new value is lower than the old value — the value decreased.
Can percentage change be calculated from zero?
No — if the old value is zero, percentage change cannot be calculated because it would require dividing by zero.
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