Flexible polyurethane foams (FPUFs) are polymeric materials which have widespread use and present a large fire risk in modern society. Accurate prediction of their fire behavior is valuable for assessing the risk they pose in any fire scenario they are involved in. Several models have been developed to predict FPUF thermal decomposition at the milligram scale. However, none of these models are able to predict pyrolysis and combustion of gram-sized or kilogram-sized FPUF samples. In this work, a combination of experiments and modeling was used to develop a complete pyrolysis model for a standard FPUF foam. Inverse modeling of thermogravimetric analysis, differential scanning calorimetry, microscale combustion calorimetry, and Controlled Atmosphere Pyrolysis Apparatus II experiments was conducted to obtain a comprehensive list of decomposition reaction kinetics, thermodynamic and transport properties that define the pyrolysis and flaming combustion of this material.