This paper explores some of the important issues that influence the magnitude of receival site grain catchments in Australia. Changes in grain harvests, transport and grain handling technologies and costs; changes in farming systems, crop yields and harvesting capacity; investments in roads and on‐farm storage and economies of size in grain receival infrastructure are shown in combination to affect the size of grain catchments in major grain‐growing regions of Australia over the last 30 years. The size of grain catchments that minimise growers’ costs of road transport of their harvested grain and their receival point charges in various time periods are determined. Differently shaped grain catchments are considered. The main finding is that the size of grain catchments that minimise farmers’ grain transport, off‐farm storage and handling costs since the mid‐1980s has consistently increased, principally due to lessening real costs of road transport, more on‐farm storage and economies of size in grain receival, despite higher grain yields and a greater intensity of cropping. These findings are consistent with the observed reduction in the number of receival sites in many grain‐growing regions of Australia. Site rationalisation is less evident in states where the receival network is owned and operated by a grower cooperative.