Economic losses and costs associated with weeds in dryland cotton production are important for growers, weeds researchers, and rural industry funding bodies when making decisions about research priorities and research and development funding. A survey was conducted to provide information on weed types and control strategies, from which estimated costs to growers were derived. We used information from the survey to estimate conventional financial losses due to weeds, and as a basis for evaluating aggregate economic (society) impacts. An economic surplus model was used to estimate the aggregate societal impact of weeds for the main cotton production region in sub-tropical Australia. The annual economic costs associated with weeds were estimated to be $19.6 million, and the on-farm financial costs were $24.7 million.