The marginal factor cost curve reflects the degree of market control held by a firm. For a perfectly competitive firm with no market control, the marginal factor cost curve is a horizontal line. For firms with more market control, especially monopsony, the marginal factor cost curve is positively sloped and lies above the average factor cost curve.

Marginal Factor Cost Curve, Monopsony

The marginal factor cost curve (MFC) for OmniKing Island Resort is displayed in the exhibit to the right. Key to this curve is that OmniKing is a monopsony buyer of workers and thus faces a positively-sloped supply curve. Larger quantities of input can be had only with higher prices.

The vertical axis measures marginal factor cost and the horizontal axis measures the quantity of input (workers). Although quantity on this particular graph stops at 10 workers, it could go higher.

This curve indicates that if OmniKing hires the first worker, then marginal factor cost is $6. Alternatively, if it hires the tenth worker, then marginal factor cost is $24.

For reference, the factor supply curve (and average factor cost curve, AFC) is also presented in the exhibit. The key observation is that the positively-sloped marginal factor cost curve (MFC) lies above the supply curve (AFC) facing OmniKing for hiring labor. The positioning of the marginal factor cost curve above the average factor cost curve reflects the mathematical relation between an average and a marginal.