Temperature Dependent Crystallinity Software is a powerful package used to determine the % crystallinity of a semi-crystalline polymer versus temperature. This new software provides an easy to use procedure which leads to an analyst-independent determination of temperature dependent crystallinity by utilizing transition enthalpies with data available mainly from the Advanced Thermal Analysis Laboratory (ATHAS) data bank for 16 different polymers. The method assumes that the heat capacity contribution of the amorphous content can be extrapolated from the melting region to substantially lower temperatures. This information, together with the ATHAS enthalpy data and the experimental curve is sufficient to calculate the percent crystallinity versus temperature.