Historical Context & Motivation
The question of what constitutes "profit" has occupied economic thinkers for centuries, yet the answer depends critically on who is asking and why. An accountant tallying a firm's books and an economist analyzing market behavior will arrive at different figures for the same firm — not because one is wrong, but because they define costs differently. This conceptual split between accounting profit and economic profit lies at the heart of modern microeconomic theory and is central to understanding how firms make entry, exit, and production decisions.
The central question this lesson addresses is deceptively simple: when a firm reports "positive profit" on its income statement, is it truly earning more than the full cost of all resources deployed — including the owner's time and the capital tied up in the business? Understanding the answer requires mastering the distinction between explicit costs, implicit costs, and the three profit categories that flow from them.
Core Principles & Definitions
Before distinguishing types of profit, we must first separate costs into two categories. Explicit costs are direct, out-of-pocket payments a firm makes to outside suppliers of inputs — wages paid to workers, rent for a storefront, raw material purchases, and utility bills. These appear on the firm's financial statements. Implicit costs, by contrast, represent the opportunity cost of using owner-supplied resources — the income the entrepreneur forgoes by not deploying those resources in their next-best alternative use. Together, explicit and implicit costs constitute total economic cost.
Accounting Profit
Economic Profit
Normal Profit
Explicit vs. Implicit Costs
Visual Explanation — Breaking Down Revenue into Cost Layers
The diagram above illustrates a firm with total revenue of $200,000. From the accountant's viewpoint (View A), the firm is profitable — it covers its explicit costs and has $50,000 remaining. But from the economist's viewpoint (View B), the owner's opportunity costs of $60,000 must also be subtracted. Because $50,000 in accounting profit falls short of the $60,000 needed to cover implicit costs, economic profit is negative $10,000. The firm would be better off if the owner redeployed resources to their next-best alternative.
Mathematical Framework
A key relationship to internalize: Accounting Profit = Economic Profit + Implicit Costs. Because implicit costs are always non-negative, accounting profit is always greater than or equal to economic profit. A firm can report positive accounting profit while simultaneously earning negative economic profit — the scenario depicted in Section 3. Conversely, if economic profit is positive, the firm is earning above what all its resources could command elsewhere, which attracts new entrants in competitive markets.
Three Profit Scenarios for a Competitive Firm
In perfect competition, a firm is a price taker: it faces a horizontal demand curve at the market price. Whether the firm earns positive, zero, or negative economic profit depends on the relationship between price and average total cost (ATC) at the profit-maximizing output where MR = MC. The following diagram shows all three scenarios side by side.
In Panel A, the market price is high enough that the firm's per-unit revenue exceeds its per-unit total cost at the MR = MC output level, generating positive economic profit equal to (P − ATC) × Q. This attracts new firms, shifting the market supply curve rightward and driving the price down until economic profit reaches zero. Panel B shows the resulting long-run equilibrium where P = minimum ATC and economic profit is zero — the firm earns normal profit only. Panel C illustrates a price below ATC, resulting in economic losses; firms exit, supply decreases, and price rises back toward the zero-economic-profit equilibrium.
Worked Example
Suppose Maria runs a small bakery. She left her job as a pastry chef at a hotel, where she earned $55,000 per year, and invested $100,000 of her savings (which had been earning 5% annual interest) into the bakery. Last year the bakery's financial records showed: total revenue = $250,000; wages paid to employees = $90,000; rent = $30,000; ingredient costs = $50,000; utilities and other expenses = $15,000.
Comparing the Three Types of Profit
| Feature | Accounting Profit | Economic Profit | Normal Profit |
|---|---|---|---|
| Formula | TR − Explicit Costs | TR − (Explicit + Implicit Costs) | Implicit Costs (i.e., accounting profit when π_econ = 0) |
| Includes Implicit Costs? | No | Yes | Is the implicit cost |
| Used By | Accountants, IRS, financial reports | Economists analyzing market efficiency | Economists defining long-run equilibrium |
| Firm Decision Signal | Tax liability and financial health | Entry/exit decisions in a market | Break-even threshold for staying in industry |
| Long-Run Competitive Equilibrium | Positive (equals implicit costs) | Zero | Being earned exactly |
Connection to Market Structure & Long-Run Equilibrium
| Concept | Perfect Competition | Imperfect Competition (Monopoly, Oligopoly, Mon. Comp.) |
|---|---|---|
| Short-Run Economic Profit | Possible (positive, zero, or negative) | Possible (often positive due to market power) |
| Long-Run Economic Profit | Zero — free entry/exit eliminates it | Can persist if barriers to entry exist (monopoly, oligopoly); zero for monopolistic competition |
| Entry/Exit Mechanism | Free entry and exit shift supply until P = min ATC | Barriers impede entry; supernormal profits may persist indefinitely |
| Role of Normal Profit | Defines the long-run resting point for all firms | Still the opportunity cost benchmark, but firms may exceed it |
The types of profit you have learned connect directly to the broader AP Microeconomics curriculum. In later units you will see that monopolists and oligopolists can sustain positive economic profit in the long run because barriers to entry prevent the competitive entry process that drives economic profit to zero. For monopolistic competition, free entry still drives economic profit to zero in the long run, but the firm does not produce at minimum ATC due to product differentiation. Understanding the zero-economic-profit condition in perfect competition provides the baseline against which all other market structures are evaluated.