A standard blackbody furnace for the calibration of commercially available radiation thermometers has been developed. This furnace has a cavity of chrome plated copper walls with an opening of 60mm in diameter. The furnace is designed so that the temperature of the cavity can be easily estimated by a resistance thermometer. It is shown that the furnace has an accuracy of 1K through the comparison with two fixed point blackbodies when the effective emissivity, the size-of-source effect and the absorption by water vapor of the air are corrected for.