Abstract: It is often assumed that the elasticity of GDP with respect to capital is one-third, but this assumes zero markups and an aggregate produc- tion function. I estimate the elasticity allowing markups to vary by industry and with a rich input-output structure. Assumptions about capital costs provide bounds on elasticity. In the United States from 1948–1995, the capital elasticity ranged from 0.19-0.32 and shifted to 0.24-0.37 by 1996-2018. Excluding housing or decapitalizing intellectual property lowers bounds to as low as 0.11-0.26. Based on these elasticities, common estimates of total factor productivity growth represent a lower bound.