Percent Change Calculator

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

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.

This calculator works with inches, percentages. You can enter values in the units shown — the calculator handles all conversions internally.

The core formula is: Percentage change = ((New − Old) / |Old|) × 100. Each step in the calculation is shown so you can verify the result manually.