Prescribed burning costs are extremely variable, even if conditions are similar. This variability complicates planning and evaluation of prescribed burning programs and budgets, resulting in imprecise projections of their economic benefits. Evaluating the worth of prescribed burning efforts in objective terms is difficult, but the continual shrinkage of USDA Forest Service budgets requires an increase in program efficiency and understanding the causes of variability for prescribed burning costs. An analysis of variance model was used to describe and quantify the relative effect of managerial and institutional factors, such as smoke emission limitations or the constraint to control all types of fires, on prescribed burning costs. Data were collected by using a questionnaire to fire and fuel managers in the USDA Forest Service's Northern, Intermountain, and Pacific Northwest Regions. Estimated prescribed burning costs were significantly affected by changes in the managerial and institutional factors, such as minimizing escape potential or complying with smoke emission standards presented to these fire managers. Contrary to our expectations, burn objective (the main reason for conducting the burn) was not a significant cost factor. Unit size of the burned area affected prescribed burning costs more than either change in slope or unit shape, both of which increase the amount of burn perimeter relative to the area burned. Costs per acre demonstrated economies of scale: the larger the unit burned, the lower its per-acre cost.