For a small manufacturer, the question "what does it actually cost us to make one unit?" often gets answered with a rough estimate rather than a real calculation. That's usually fine until margins get tight or a customer negotiates on price — at which point an inaccurate cost figure can mean accepting an order that actually loses money.

The three cost categories

Every unit of finished goods carries three types of cost, and each needs a different allocation method.

1. Direct material cost

This is the most straightforward: the cost of raw materials that go directly into the product, based on the bill of materials. The main source of error here isn't the calculation — it's using outdated purchase prices instead of current ones, which understates cost when material prices rise.

2. Direct labor cost

The labor time genuinely spent producing that specific unit or batch, valued at actual wage cost including any statutory contributions (EOBI, SESSI). This is often estimated rather than tracked, which is fine for a rough figure but will drift from reality if production times change and the estimate isn't updated.

3. Overhead allocation

This is where most small manufacturers get it wrong — not because it's complicated, but because it's often skipped entirely. Overhead includes rent, utilities, equipment depreciation, and indirect labor (supervisors, quality checks) that isn't tied to one specific product. The simplest reliable method is to allocate overhead as a percentage of direct labor cost or machine hours, applied consistently across all products.

The mistake that hurts margins most: pricing based only on direct material and labor, with overhead left out entirely. A product can look profitable on a simple cost basis and still lose money once rent, utilities, and equipment costs are properly allocated.

A simple monthly costing routine

  1. Confirm current raw material prices are reflected in the bill of materials — not last quarter's prices.
  2. Review actual production time per batch against the labor estimate used in costing, and adjust if they've drifted apart.
  3. Recalculate the overhead allocation rate using last month's actual overhead costs, not a fixed assumption from when the business started.
  4. Compare the resulting cost per unit against your current selling price for each product line, and flag anything with a shrinking margin.

A Manufacturing module tied to inventory and the general ledger keeps material costs, labor allocation, and overhead current automatically, instead of a quarterly manual recalculation.

See the Manufacturing module →