A single strand of human hair is stronger than a copper wire of the same thickness.

Human hair is a biological polymer composite primarily made of alpha-keratin. This protein is structured in a complex hierarchy of coiled-coil molecular chains. These chains are bundled into intermediate filaments and then into macrofibrils, creating a structure similar to high-strength industrial cables. This architecture allows a single healthy strand to withstand a tension of approximately 100 grams without snapping.The strength of hair is largely due to disulfide bonds, which are strong covalent chemical links between sulfur atoms in the cysteine amino acids. These bonds act as cross-links that prevent the protein chains from sliding past each other under stress. Research conducted at the University of California, San Diego, has shown that hair possesses a high strength-to-weight ratio. This makes it comparable to materials like steel and aluminum in terms of tensile strength relative to its density.On average, a human head has about 100,000 to 150,000 hair follicles. If each strand can hold 100 grams, a full head of hair could theoretically support a weight of 10 to 15 metric tons. This is equivalent to the weight of two adult African elephants, which typically weigh between 5 and 7 tons each. However, the actual limit is usually determined by the strength of the scalp and hair roots rather than the hair shaft itself.