Cost Classification: Direct, Indirect, Fixed and Variable Costs
How accountants group costs, with clear examples and a worked classification exercise.
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Why classify costs?
A business cannot control what it cannot describe. Classifying costs lets managers work out what a product really costs, predict how costs change when output changes, and decide where to cut spending. Every later topic in cost accounting, such as overhead absorption, break-even analysis and budgeting, depends on classifying costs correctly first.
1. By traceability: direct and indirect costs
The question here is: can I trace this cost to a specific product, job or department?
| Type | Meaning | Examples (bicycle maker) |
|---|---|---|
| Direct materials | Materials that become part of the product | Aluminium frames, tyres |
| Direct labour | Wages of workers who make the product | Assembly-line wages |
| Direct expenses | Other costs traceable to a product | Hire of a special machine for one order |
| Indirect costs (overhead) | Costs that serve many products and cannot be traced to one | Factory rent, supervisor’s salary, factory lighting |
Direct materials plus direct labour plus direct expenses make up the prime cost. Adding production overhead gives the full cost of production. Read more in direct cost and overhead.
2. By behaviour: fixed, variable and semi-variable costs
The question here is: what happens to this cost when output goes up or down?
| Type | Behaviour | Examples |
|---|---|---|
| Fixed | Stays the same in total within the normal range of activity | Rent, insurance, salaried staff |
| Variable | Rises and falls in proportion to activity | Raw materials, packaging, sales commission |
| Semi-variable | Has a fixed part and a variable part | Phone bill with line rental plus call charges |
| Step cost | Fixed for a range, then jumps | Renting a second warehouse once the first is full |
Example. A workshop has fixed costs of 10,000 and a variable cost of 4 per unit.
| Units | Variable cost | Fixed cost | Total cost | Cost per unit |
|---|---|---|---|---|
| 3,000 | 12,000 | 10,000 | 22,000 | 7.33 |
| 5,000 | 20,000 | 10,000 | 30,000 | 6.00 |
Total fixed cost stays at 10,000, so the cost per unit falls as output rises. Variable cost per unit stays at 4.
3. By function: where the cost arises
| Function | Examples |
|---|---|
| Production (manufacturing) | Materials, factory wages, factory rent and power |
| Selling and distribution | Advertising, sales staff, delivery vehicles |
| Administration | Office salaries, accounting, management |
| Finance | Loan interest, bank charges |
Only production costs are normally included in the cost of inventory. The others are charged to the period in which they occur.
Other useful classifications
- Product costs vs period costs: product costs attach to units made; period costs are charged to the time period.
- Controllable vs uncontrollable: whether a particular manager can influence the cost.
- Relevant vs irrelevant: whether a cost changes because of a decision. See sunk cost and opportunity cost.
Worked example: classify a bicycle company’s costs
| Cost | Traceability | Behaviour | Function |
|---|---|---|---|
| Aluminium frames | Direct material | Variable | Production |
| Assemblers’ wages (paid per bike) | Direct labour | Variable | Production |
| Factory rent | Indirect | Fixed | Production |
| Showroom advertising | Indirect | Fixed (usually) | Selling |
| Fuel for delivery van | Indirect | Variable | Distribution |
| Managing director’s salary | Indirect | Fixed | Administration |
Common mistakes
- Mixing up the two questions. “Direct or indirect” and “fixed or variable” are separate. Direct labour can be fixed (a salaried machinist) and indirect costs can be variable (factory electricity).
- Calling a cost fixed forever. Fixed costs are fixed only within a range. Step costs jump when capacity is exceeded.
- Forgetting the cost per unit. Fixed cost per unit falls as output rises; variable cost per unit stays constant.
Quick check
1. Is the wage of a salaried machine operator who works only on Product X direct or indirect, and fixed or variable?
Direct labour (it traces to Product X), and fixed (the salary does not change with output).
2. Fixed costs are 20,000 and variable cost is 5 per unit. What is the total cost of 4,000 units?
20,000 + (5 × 4,000) = 40,000.
Ready to practise? Try Problem 1 in the cost accounting problem bank.
Frequently asked questions
What is the difference between direct and indirect costs?
Direct costs can be traced to a specific product, job or department. Indirect costs serve more than one product and must be shared out through overhead absorption.
What is a semi-variable cost?
A cost with both a fixed and a variable element, such as a utility bill with a standing charge plus a charge per unit used.
Why does fixed cost per unit fall when output rises?
The total fixed cost stays the same but is spread over more units.
Keep learning
This lesson is for general learning. Terminology and layouts vary by syllabus and country.
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