This paper describes the development of a ship air emissions calculator, which will be part of the ECOMARPOL platform of the Intelligent Research Infrastructure for Shipping, Supply Chain, Transport and Logistics (EN.I.R.I.S.S.T.). The tool developed with the Python programming language and is based on a variant of the Bottom-up method. The input parameters are the main particulars of one or more ships and produces results in the form of tables and diagrams for the analysis of ship air emissions by ship type, emission type, speed and age. The tool may be used for different vessels and calculates air emissions including: carbon dioxide (CO2), sulphur oxides (SOx), nitrogen oxides (NOx) and particulate matter (PM). Furthermore, this paper presents two illustrative applications that showcases the potential of the developed tool. The first one used departure and arrival data of 100 ships within the European Economic Area (EEA) in 2018, while for the second, Automatic Identification System (AIS) movement data of a Bulk Carrier in the Baltic Sea for 24 hours were collected. The development of such tools is considered important as they can contribute to establish appropriate measures for reducing air emissions and help the shipping industry to comply with existing regulations.