About 31 tons of copper make up the Statue of Liberty’s exterior. That copper forms the statue’s thin outer skin, rather than its supporting structure.
The copper sheets were hammered into shape in France and attached to an iron framework. They are only about 3/32 of an inch thick—roughly the thickness of two American pennies. This lightweight construction allowed the enormous figure to be assembled around Gustave Eiffel’s flexible internal framework.
The statue’s total weight is far greater than its copper skin alone. Its iron or steel framework accounts for much of the remaining weight, while the pedestal and foundation add vastly more. A frequent mix-up is to quote the statue’s overall weight—often given as about 225 tons—as the amount of copper. That figure refers to the complete statue’s structure, not just its exterior cladding.
The copper gradually developed its familiar green patina through oxidation. Rather than being painted green, the surface changed naturally over time, and conservators regard the patina as protective.