Rainer was born in Graz, Austria-Hungary.[3] In 1917, at age 18, he was measured at 122.55 cm (4 ft 0.25 in). A typical defining characteristic of dwarfism is an adult height below 147 cm (4 ft 10 in). Then, likely as a result of a pituitary tumor, he had a dramatic growth spurt so that by 1931 at the age of 32 he had reached a height of 218 cm (7 ft 2 in).[4] As a result of his gigantism he became bedridden for the rest of his life.[3] When he died in 1950 (age 51) he had reached a height of 234 cm (7 ft 8 in).[5] His feet measured 33.3 cm (13.1 inches), going from EUR shoe size 43 (US size 10) at aged 19 to size 53 (US 20) only three years later.[6] His hands measured 23.9 cm (9.4 inches) and he weighed 109 kg (241 pounds).