# Part 1 Section D.1.2. Variable and Absorption Costing　直接原価計算と全部原価計算

## 演習

### 計算問題 – 直接原価と全部原価

#### Using absorption costing

##### Manufacturing cost per unit

Cost to manufacture 100,000 units
= \$400,000 materials + \$100,000 direct labor + \$20,000 variable manufacturing overhead + \$200,000 fixed manufacturing overhead = \$720,000
Cost per unit = \$720,000 ÷ 100,000 = \$7.20 per unit.

##### Ending inventory

10,000 units in beginning inventory + 100,000 units manufactured – 106,000 units sold = 4,000 units in ending inventory.
4,000 units in ending inventory × \$7.20 cost per unit = \$28,800 inventory value.

##### Net income

Sales = 106,000 units sold × \$12 price per unit = \$1,272,000.
Cost of goods sold
= Beginning inventory = \$72,000 + COGM \$720,000 – ending inventory \$28,800
= \$763,200
Gross profit = \$1,272,000 – \$763,200 = \$508,800
= \$80,000 variable cost + \$300,000 fixed costs = \$380,000
Net income
= \$508,800 gross profit – \$380,000 selling & administrative expense = \$128,800

#### Using variable costing

##### Manufacturing cost per unit

Cost to manufacture 100,000 units
= \$400,000 materials + \$100,000 direct labor + \$20,000 variable manufacturing overhead = \$520,000
Cost per unit = \$520,000 ÷ 100,000 = \$5.20 per unit.

##### Ending inventory

4,000 units in ending inventory × \$5.20 cost per unit = \$20,800 inventory value.

##### Net income

Sales = 106,000 units sold × \$12 price per unit = \$1,272,000.
Variable cost and contribution margin:
Variable manufacturing cost: \$5.20 × 106,000 = \$551,200
Variable selling & administrative expense: \$80,000
Total variable costs \$551,200 + \$80,000 = \$631,200
Contribution margin = Sales \$1,272,000 – Total variable costs \$631,200 = \$640,800
Fixed costs:
Fixed manufacturing costs \$200,000 + Fixed selling & administrative expense \$300,000
= \$500,000
Net income
= \$640,800 contribution margin – \$500,000 fixed manufacturing, selling & administrative expense
= \$140,800

#### The reason why two calculations for income might differ

The difference in incomes is caused by the treatment of fixed manufacturing overhead.

Absorption costing treats this cost as a product cost that is held in inventory until the goods are sold; variable costing treats fixed manufacturing overhead as a period cost, showing it as an expense immediately.

Because inventory decreased, absorption costing would expense all of the current month’s fixed manufacturing overhead as well as some of the costs that were previously deferred in the prior period’s inventory; variable costing would only expense the current month’s amount, resulting in a higher income.

##### Absorption costing　全部原価計算のメリット
• The advantages of using absorption costing are:
• It is required for external reporting.
• It matches all manufacturing costs with revenues.
##### Variable costing　直接原価計算のメリット
• The advantages of using variable costing are:
• Data required for cost-volume-profit analysis can be taken directly from the statement.
• The profit for a period is not affected by changes in inventories.
• Profits vary directly with sales volume.
• Unit product costs do not contain fixed costs that are often unitized, a practice that could result in poor decision-making.
• Because fixed costs are period cost, they are more predictable and controllable.
• The impact of fixed costs on profits is emphasized.
• It is easier to estimate a product’s profitability.
• Aids in reporting and forecasting contribution margin.
• It ties in with cost control measures such as flexible budgets. 