IRG2016 is a geoid model for Iran, computed by the National Cartographic Center (NCC). The IRG2016 modelled by radial basis functions (RBFs). The input observations were 21525 newly-refined gravity data supplied by the NCC of Iran. The IRG2016 model was fitted to more than 1400 GNSS/levelling control points over Iran. The resulting height reference surface shows an RMS value of approximately 23 cm for the difference in geoidal height at the independent control points. In this program, the input data can be introduced based on pointwise or using an input file and can calculate the geoidal height in two ways, "2.5'*2.5' grid interpolation" or "Single calculation".