The degree of monopoly power is measured in terms of difference between.
The degree of monopoly power is measured in terms of difference between Marginal cost and the price. In a perfectly competitive market, price equals marginal cost and firms earn an economic profit of zero. In a monopoly, the price is set above marginal cost and the firm earns a positive economic profit. The degree of monopoly. Market power is the ability to charge a price above marginal cost. A firm in a competitive market produces where P=MC. ... This shows us how much of a 'mark-up' the firm is charging above its marginal cost, as a proportion of its price.