Urea is a major source of nitrogen in the world. The use of urea in the production of NPKs offers substantial cost savings over other raw materials as ammonium nitrate as source of nitrogen. KT offers three major routes which are equivalent on a cost basis. The choice will be fixed according to the client raw material capabilities (production of urea, several P20 S sources, … ). The present paper compares the three best economic routes. It demonstrates that the best way consists in using a straight concentrated urea melt which is partly diluted with the washing water from the scrubber. A table shows the cost benefits resulting from the use of urea instead of ammonium nitrate in the production of 15-15-15 NPK in a 1000 MTPD plant. All three processes are described technically and the main economical factors such as material costs, investment and energy consumption are compared to an AN based NPK production plant.