Absorption costing: formula, example and variable costing compared

Absorption costing charges every unit with its direct costs plus a share of all indirect costs: full cost per unit = direct cost per unit × (1 + overhead rate). The result is what one product, order or service actually costs the company, and therefore the floor below which any selling price gives away margin.

For a controller this is rarely a one-off calculation. Unit cost connects the quotation the sales team works from, the inventory valuation on the balance sheet and the margin analysis in the monthly report. When actual output differs from the volume the overhead rate was built on, unit cost moves without a single purchase or sale taking place. That volume variance is the most common source of unexplained margin swings, and the first thing to rule out before looking at purchase prices or discounts.

What is absorption costing?

The method allocates the full cost of running the business to the units it produces. Two types of cost come together in that figure. Direct costs are traceable to the unit: material consumption, purchase value, direct hours and subcontracted work. Indirect costs belong to the organisation as a whole — production management, maintenance, premises, selling and administration — and have to be allocated through a driver.

The alternative is variable costing, which charges only the costs that move with volume and leaves fixed overhead in the income statement as a period cost. The same company therefore has two valid unit costs; which one you need depends on the decision in front of you. The first is also called full costing.

The absorption costing formula

The calculation works per product, per order or per billable hour; only the unit changes.

Overhead rate = total indirect costs ÷ total direct costs at normal capacity × 100

Full cost per unit = direct cost per unit × (1 + overhead rate)

1. Determine direct material per unit: standard consumption times purchase price, including an allowance for scrap and rejects.
2. Determine direct labour: standard time per unit times a loaded hourly rate, so including employer charges, holidays and absence.
3. Group indirect costs by the way they arise. Two groups at minimum: production overhead, and selling plus administration.
4. Pick a driver per group — direct cost, direct hours, machine hours or floor space — and set normal capacity: the volume you reach on average over several years, not this year's volume.
5. Divide each cost group by that base and add the resulting rate to the direct cost.

Absorption costing example

A manufacturer produces 40,000 units a year at normal capacity. Direct costs are € 50.00 per unit, € 2,000,000 in total. Indirect costs amount to € 1,280,000: € 800,000 of production overhead and € 480,000 of selling and administration. The overhead rates are therefore 800,000 ÷ 2,000,000 = 40% and 480,000 ÷ 2,000,000 = 24%.

Item	Per unit
Direct material	€ 18.50
Direct labour (0.75 hours × € 42.00)	€ 31.50
Direct cost	€ 50.00
Production overhead (40%)	€ 20.00
Manufacturing cost	€ 70.00
Selling and administration (24%)	€ 12.00
Full cost per unit	€ 82.00

At a selling price of € 98.00 that leaves € 16.00 per unit. If € 160,000 of the indirect costs are genuinely variable — energy, consumables, outbound freight — the variable cost per unit is € 54.00 and the contribution margin € 44.00. The € 28.00 gap is not an error: it is the fixed overhead that absorption costing allocates to the unit and variable costing does not.

If output falls to 32,000 units, the € 1,120,000 of fixed overhead stays in place and only the variable part follows volume. Indirect cost per unit rises to € 39.00 and full cost to € 89.00: eleven percent higher without any purchase price moving. Base the rate on actual output and you calculate your own price increase in a falling market. Keep charging the old 64% and € 224,000 stays unabsorbed — the volume variance, which belongs in the variance analysis as a separate result.

Full cost or variable cost?

There is no benchmark for the level of a unit cost, but there is one for the choice of method. It follows the decision:

• Price lists and long-term calculation: full cost. Across the life of a product every cost has to be recovered, overhead included.
• Inventory valuation: full cost, but only the manufacturing share. Selling and administrative costs do not belong on the balance sheet. How much production overhead may be capitalised differs per reporting framework; document the choice in your accounting policies and keep it stable over the years.
• Incremental order, make-or-buy, phasing out a product: variable cost, with contribution margin as the test. Fixed costs run on whether you accept the order or not.
• Floor for a discount: variable cost in the short term, full cost as soon as the discount becomes structural. An order below full cost is defensible as an exception and fatal as a habit.

The common mistake is treating full cost as a decision number. An order at € 70.00 per unit looks loss-making against a full cost of € 82.00, yet it still contributes € 16.00 per unit against a variable cost of € 54.00 for as long as capacity sits idle.

From unit cost to selling price

Full cost is the floor of the price, not the price itself. If you price at cost plus a mark-up, watch the difference between mark-up and margin: € 82.00 plus a 20% mark-up is € 98.40, a 16.7% margin on the selling price rather than 20%. That conversion is covered in the article on gross margin calculation; the contribution margin from the example above is the input for the break-even point calculation.

Pitfalls in absorption costing

• Basing the overhead rate on actual output. Unit cost then rises exactly when sales fall, and a price increase in a shrinking market accelerates the decline. Use normal capacity and report the difference separately.
• One overhead rate for the whole company. A labour-intensive and a machine-intensive line have different cost structures. A single driver lets one line subsidise the other and makes the product mix impossible to steer.
• An hourly rate that is too clean. Without employer charges, holidays, absence and indirect hours a rate sits twenty to forty percent too low, and that error is in every unit.
• Leaving scrap and inventory differences out of material consumption. The calculation uses theoretical consumption, the inventory records the actual figure. The gap belongs in the unit cost, not in a residual account.
• Treating intercompany transfer prices as cost. A sister company's price already contains a margin. At group level only the cost after eliminating intercompany transactions counts.

Frequently asked questions

How do you calculate absorption costing?

Add direct material and direct labour per unit, then add an overhead rate for the indirect costs. That rate is total indirect cost divided by the chosen allocation base at normal capacity. At € 50.00 of direct cost and a 64% rate, full cost comes to € 82.00 per unit.

What is the difference between absorption costing and variable costing?

The first allocates fixed overhead to the unit, the second charges only costs that move with volume and treats fixed overhead as a period cost. Use full cost for price lists and inventory valuation, and variable cost for decisions on incremental orders or outsourcing.

Does the method change reported profit?

Yes, because fixed overhead travels with inventory. Produce more than you sell and part of the fixed cost is capitalised in stock, which lifts profit; sell out of stock and the reverse happens. Variable costing shows no such effect, so the two methods report different results for the same period.

How often should the rates be recalculated?

At least quarterly, and always right after a new purchase contract, a wage round or a structural change in capacity. Revise the drivers themselves only at budget time: change them mid-year and no margin comparison between periods remains reliable.

Unit cost in your monthly reporting

The calculation is not the hard part; putting it next to actuals every month is, because overhead rates usually live in a spreadsheet nobody updates. In Smartbooks you split the account structure for that: subfolders for direct and indirect cost form their own subtotals, and ledger accounts holding both kinds of cost can be split before they reach the analysis. Produced or sold volume is stored as a metric with manual input, after which a second metric uses a formula that references those subtotals and that volume. A dynamic addition places the line directly under the cost of sales row in the income statement, and the cost centre picker shows the same build-up per production line or site — with the caveat that a formula cannot reference one cost centre from another.

More formulas and benchmarks from this series are in the knowledge center, or see how reporting is built up.