Within the framework of the scaling theory, a fundamental equation of state (FEoS) of carbon dioxide has been developed, which has a working area: in pressure up to 500 MPa and in temperature up to 1000 K. The uncertainty in describing the FEoS of thermal and caloric properties of carbon dioxide is estimated based on statistical characteristics, including the calculation of ADD (absolute average deviation) and BIAS (systematic deviation) according to the NIST method and standard deviation, RMS, GOST 34100.3-2017. On the basis of the same statistical characteristics, an analysis was made of the Kaplun–Meshalkin three-parameter equation of state, the working area of which was determined by its authors: by pressure from 0.1 MPa to 100 MPa and by temperature from 220 K to 1000 K. It is shown that the accuracy estimates of the Kaplun–Meshalkin EoS (KM) allow us to recommend this equation for engineering calculations of only the thermal surface of carbon dioxide in the supercritical state in the range from 320 K to 1000 K. The values  for the supercritical fluid, liquid, gas, saturated vapor and saturated liquid are calculated, which are respectively equal to: 19.2, 303, 14.7, 83 and 1069. and calculated respectively on the basis of FEoS and Kaplun–Meshalkin's EoS. The results obtained are discussed.