A ship’s productivity is measured by the number of loaded days at sea. Time in ballast, time off hire and port time are the three main factors that influence productivity. Since the tanker segment has limited possibilities for backhauls, it is common that time in ballast accounts for about 50% of their annual voyages. Time off hire depend on the time spent on essentials as repair and surveys, and of course conditions in the freight market. The overall shipping industry suffers from a continuous imbalance of supply and demand (Stopford, 2009). The last couple of years has been challenging, as new external factors makes demand less predictable (Bellemare, 2017). For the tanker industry, 2015 was probably the best year since the market crisis in 2008 (UNCTAD, 2016, p. 57). However, in 2016, the fortune faded (BIMCO, 2017). Time use at port is the last factor to influence productivity. As an element that is to some extent controllable, port time is a central and widely discussed topic. The functions of a port are crucial for a ship’s productivity. Especially since port charges are a major part of a ship’s voyage cost (Stopford, 2009). As a part of the Interreg project - NØKS II (Nærskipsfart i Øresund / Kattegat/Skagerrak), this research addresses the topic of port time. NØKS II focuses on facilitation and development of sea transportation in a specified area. The aim is to evolve an attractive, environmental, safe and sustainable freight flow between Norway, Sweden and Denmark (Vestfold Fylkeskommune, 2015). This study has been conducted based upon analysis of AIS-data from the year 2016. The total amount of time the vessel that arrived or departed from the selected ports are measured and classified as active or idle time. The majority of the idle time is when the vessel is entering the anchorage area which means that the idle time occurs under an “inward voyage”. The fact is that more than two vessels are often calling to a refinery at the same time, thus the build-up starts. Every ship owner or charter want as many sailing days pr. ship since this when they are making their money, not when the ship is at anchor, also known as idle time. The paper presents the extent of idle time in oil ports by the use of AIS data. The study is performed on two ports, one in Sweden and one I Norway. The paper presents a comperative study between ports in Norway and Sweden.  In Sweden the choice of port landed on Brofjorden, an oil port owned by the largest fuel company in Sweden, Preem AB (Preem AB, 2017). In Norway Slagentangen refinery owned by Norwegian Esso was selected.