How to Calculate Percent Change
What is Percent Change?
Percentage change measures the relative change between an old value and a new value, expressed as a percentage of the old value. It tells you how much something has grown or shrunk in relative terms — essential for comparing changes of different magnitudes.
Formula
Step-by-Step Guide
- 1Percentage change = ((New − Old) / |Old|) × 100
- 2Positive result = increase | Negative result = decrease
- 3Note: a 50% increase followed by a 50% decrease does NOT return to the original
Worked Examples
Frequently Asked Questions
What is Percent Change?
Percentage change measures the relative change between an old value and a new value, expressed as a percentage of the old value. It tells you how much something has grown or shrunk in relative terms — essential for comparing changes of different magnitudes
How accurate is the Percent Change calculator?
The calculator uses the standard published formula for percent change. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.
What units does the Percent Change calculator use?
This calculator works with inches, percentages. You can enter values in the units shown — the calculator handles all conversions internally.
What formula does the Percent Change calculator use?
The core formula is: Percentage change = ((New − Old) / |Old|) × 100. Each step in the calculation is shown so you can verify the result manually.
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