Costs are measured in units of nominal currency by convention. Cost accounting can be viewed as translating the Supply Chain (the series of events in the production process that, in concert, result in a product) into financial values.
There are at least four approaches:
Classical Cost Elements are:
In the early industrial age, most of the costs incurred by a business were what modern accountants call "variable costs" because they varied directly with the amount of production. Money was spent on labor, raw materials, power to run a factory, etc. in direct proportion to production. Managers could simply total the variable costs for a product and use this as a rough guide for decision-making processes.
Some costs tend to remain the same even during busy periods, unlike variable costs which rise and fall with volume of work. Over time, the importance of these "fixed costs" has become more important to managers. Examples of fixed costs include the depreciation of plant and equipment, and the cost of departments such as maintenance, tooling, production control, purchasing, quality control, storage and handling, plant supervision and engineering. In the early twentieth century, these costs were of little importance to most businesses. However, in the twenty-first century, these costs are often more important than the variable cost of a product, and allocating them to a broad range of products can lead to bad decision making. Managers must understand fixed costs in order to make decisions about products and pricing.
For example: A company produced railway coaches and had only one product. To make each coach, the company needed to purchase $60 of raw materials and components, and pay 6 laborers $40 each. Therefore, total variable cost for each coach was $300. Knowing that making a coach required spending $300, managers knew they couldn't sell below that price without losing money on each coach. Any price above $300 became a contribution to the fixed costs of the company. If the fixed costs were, say, $1000 per month for rent, insurance and owner's salary, the company could therefore sell 5 coaches per month for a total of $3000 (priced at $600 each), or 10 coaches for a total of $4500 (priced at $450 each), and make a profit of $500 in both cases.
This method tended to slightly distort the resulting unit cost, but in mass-production industries that made one product line, and where the fixed costs were relatively low, the distortion was very minor.
An important part of standard cost accounting is a variance analysis which breaks down the variation between actual cost and standard costs into various components (volume variation, material cost variation, labor cost variation, etc.) so managers can understand why costs were different from what was planned and take appropriate action to correct the situation.
As a result of the above, using standard cost accounting to analyze management decisions can distort the unit cost figures in ways that can lead managers to make decisions that do not reduce costs or maximize profits. For this reason, managers often use the terms "direct costs" and "indirect costs" to replace the standard costing, to better reflect the way allocation of overhead is actually calculated. Indirect costs (often large) are usually allocated in proportion to either labor cost, other direct costs, or some physical resource utilization.
Managers using the standard cost for 40 coaches per month would likely reject an order for 100 coaches (to be produced in one month) if the selling price was only $300 per unit, seeing that it would result in a loss of $25 per unit. If they analyzed the fixed vs. variable cost distinction, they would see clearly that filling this order would result in a contribution to fixed costs of $240 per coach ($300 selling price less $60 materials) and would result in a net profit for the month of $13,400 (($240 x 100) - 10,600).
As business became more complex and began producing a greater variety of products, the use of cost accounting to make decisions to maximize profitability came under question. Management circles became increasingly aware of the Theory of Constraints in the 1980s, and began to understand that "every production process has a limiting factor" somewhere in the chain of production. As business management learned to identify the constraints, they increasingly adopted throughput accounting to manage them and "maximize the throughput dollars" (or other currency) from each unit of constrained resource.
| Overhead Cost by Department | Total Cost | Hours Available per month | Cost per hour |
| Foundry | $ 7,300.00 | 160 | $45.63 |
| Metal shop | $ 3,300.00 | 160 | $20.63 |
| Total | $10,600.00 | 320 | $33.13 |
| Standard Cost Accounting Analysis | Streetcars | Rail coach |
| Monthly Demand | 15 | 40 |
| Price | $280 | $350 |
| Foundry Time (hrs) | 3.0 | 2.0 |
| Metalwork Time (hrs) | 1.5 | 4.0 |
| Total Time | 4.5 | 6.0 |
| Foundry Cost | $136.88 | $ 91.25 |
| Metalwork Cost | $ 30.94 | $ 82.50 |
| Raw Material Cost | $120.00 | $ 60.00 |
| Total Cost | $287.81 | $233.75 |
| Profit per Unit | $ (7.81) | $116.25 |
| Throughput Cost Accounting Analysis | Decline Contract | Take Contract |
| Coaches Produced | 40 | 34 |
| Streetcars Produced | 0 | 15 |
| Foundry Hours | 80 | 113 |
| Metal shop Hours | 160 | 159 |
| Coach Revenue | $14,000 | $11,900 |
| Streetcar Revenue | $ 0 | $ 4,200 |
| Coach Raw Material Cost | $(2,400) | $(2,040) |
| Streetcar Raw Material Cost | $ 0 | $(1,800) |
| Throughput Value | $11,600 | $12,260 |
| Overhead Expense | $(10,600) | $(10,600) |
| Profit | $1,000 | $1,660 |
Accountants assign 100% of each employee's time to the different activities performed inside a company (many will use surveys to have the workers themselves assign their time to the different activities). The accountant then can determine the total cost spent on each activity by summing up the percentage of each worker's salary spent on that activity.
A company can use the resulting activity cost data to determine where to focus their operational improvement efforts. For example, a job based manufacturer may find that a high percentage of their workers are spending their time trying to figure out a hastily written customer order. Via ABC, the accountants now have a currency amount that will be associated with the activity of "Researching Customer Work Order Specifications". Senior management can now decide how much focus or money to budget for the resolutions of this process deficiency. Activity-based management includes (but is not restricted to) the use of activity-based costing to manage a business.
This method is used particularly for short-term decision-making. Its principal tenets are:
Thus it does not attempt to allocate fixed costs in an arbitrary manner to different products. The short-term objective is to maximize contribution per unit. If constraints exist on resources, then Managerial Accounting dictates that marginal cost analysis be employed to maximize contribution per unit of the constrained resource (see Development of Throughput Accounting, above).