Biomass transport cost from field to a conversion facility is a major component of biofuel production cost. Several studies have provided a general framework, independent of location, for maximising cost competitiveness of bioenergy plants. The majority of these studies assume uniform spatial distribution of biomass and road network, independent of the size of the biorefinery. Although this assumption simplifies the theoretical derivation, it may not be suitable for practical cases. We develop a more generic biomass transport model that allows biomass yield density and road network vary with transport radius, and then derive a formula for determining biomass transport cost, which more accurately represents changes in biomass transport cost with conversion plant capacity. The formula can be used to evaluate locations and investment opportunities in large scale biofuel production. (C) 2015 Elsevier Ltd. All rights reserved.