3.7 Firms' Costs, Revenue and Objectives


2026 📋 Syllabus Objectives

By the end of this topic, you should be able to:

  • 3.7.1 Define total cost (TC), average total cost (ATC), fixed cost (FC), variable cost (VC), average fixed cost (AFC) and average variable cost (AVC)
  • 3.7.2 Calculate TC, ATC, FC, VC, AFC and AVC; draw and interpret diagrams showing how output changes affect costs
  • 3.7.3 Define total revenue (TR) and average revenue (AR)
  • 3.7.4 Calculate TR and AR; explain how sales influence revenue
  • 3.7.5 Explain the objectives of firms: survival, social welfare, profit maximisation and growth

📘 PART 1: Costs of Production

What Are Costs of Production?

When a firm produces goods or services, it has to spend money on the things it needs — such as workers, raw materials, buildings, and equipment. These spending amounts are called costs of production — the money a firm spends in order to produce its output.

Costs are split into different types depending on whether they change when the firm produces more or less.


1. Fixed Costs (FC)

Fixed costs are costs that stay the same no matter how much (or how little) a firm produces. Even if the firm produces zero units, it still has to pay these costs.

Think of it this way: even if a bakery bakes zero loaves one day, it still has to pay its rent and its manager's salary.

Examples of fixed costs:

  • Rent on a building or factory
  • Manager's salary
  • Insurance payments
  • Bank loan repayments
  • Interest on loans

On a graph: Fixed cost appears as a horizontal straight line — it does not go up or down as output changes.

Cost ($)
  |
  |____________________________  ← Fixed Cost (e.g. $4,000)
  |
  +----------------------------→ Output

2. Variable Costs (VC)

Variable costs are costs that change directly with output. When a firm produces more, variable costs go up. When it produces less, they go down. If a firm produces nothing, variable costs are zero.

Example: If a factory makes more shirts, it needs more fabric and more workers' hours — both of these are variable costs.

Examples of variable costs:

  • Raw materials (e.g. wood, fabric, metal)
  • Wages of production workers
  • Fuel and electricity used in production
  • Packaging costs

On a graph: Variable cost starts at zero and slopes upward as output increases.

Cost ($)
  |               /
  |             /
  |           /  ← Variable Cost
  |         /
  |       /
  |     /
  |   /
  | /
  +----------------------------→ Output

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