cost curve A curve relating costs to the quantity of a good produced. The total cost curve or schedule shows total costs at each level of output; the average cost curve shows total costs divided by quantity produced; and the marginal cost curve shows the addition to total costs caused by any increase in output. The marginal cost curve thus shows the slope of the total cost curve at any level of output. Any of these curves may be drawn for fixed costs, variable costs, or both combined. Cost curves can be constructed for the short run, in which few inputs can be adjusted, or for the long run, in which all inputs can be adjusted. A U-shaped average cost curve means ...