True Manufacturing Cost: Direct Labour + Materials + Overhead Allocation
- The Product That Was Priced 31% Below Its True Cost
- The Three Components of True Manufacturing Cost
- Overhead Allocation: Choosing the Right Driver
- How to Calculate Your Overhead Rate
- How AskBiz and Xero Build Your True Cost Picture
- Contribution Margin Analysis: When Full Cost Is Not the Only Lens
- Before and After: A Singapore Electronics Manufacturer
- Know Your True Cost Before You Price
True manufacturing cost is not just materials and direct labour. Overhead — rent, utilities, indirect labour, depreciation, insurance — must be allocated to each product to give an accurate picture of unit cost and product-level profitability. Most SMB factories get this wrong.
- The Product That Was Priced 31% Below Its True Cost
- The Three Components of True Manufacturing Cost
- Overhead Allocation: Choosing the Right Driver
- How to Calculate Your Overhead Rate
- How AskBiz and Xero Build Your True Cost Picture
The Product That Was Priced 31% Below Its True Cost#
A Glasgow electronics manufacturing SME with three product lines had a basic cost model: direct materials + direct labour + a 25% mark-up for overheads. The 25% mark-up had been set years earlier based on a rough calculation and never updated. When a management accountant was engaged to rebuild the cost model properly, she found that overhead costs as a proportion of total cost had grown to 38% — driven by increased rent after a move to larger premises, higher energy costs, and investment in additional indirect headcount (a quality inspector and a production planner). One product line — a complex controller unit — was particularly overhead-intensive because it used a specialised jig and required 40% more quality inspection time per unit than the other lines. When overhead was allocated based on actual inspection and machine time rather than a blanket percentage, the controller unit's true cost was 31% higher than the model had assumed. It had been sold at a loss for two years. Identifying this was the first step to either repricing the line or redesigning it to reduce overhead intensity.
The Three Components of True Manufacturing Cost#
True unit manufacturing cost has three components. First, direct materials: every raw material and bought-in component in the BOM, at current purchase price, adjusted for yield loss. This should be the most accurately tracked element in most factories. Second, direct labour: the cost of operator time directly producing the product — wages plus employer statutory contributions — at the actual or standard time per unit. Do not confuse direct labour (hands-on production time) with indirect labour (supervision, maintenance, quality inspection) — the latter is overhead. Third, overhead: all factory costs that cannot be directly attributed to a single product — rent, rates, utilities, indirect labour (supervisors, maintenance, quality), equipment depreciation, maintenance, insurance, consumables not in the BOM. Overhead must be allocated to products using a rational basis — typically direct labour hours, machine hours, or a combination.
Overhead Allocation: Choosing the Right Driver#
The most common overhead allocation basis in SMB manufacturing is direct labour hours — overhead is spread across products in proportion to the direct labour hours each product consumes. This is reasonable when labour intensity drives most overhead consumption. However, it becomes inaccurate when products have very different machine intensities or very different quality inspection requirements. A product made almost entirely by automation but requiring minimal labour should not be penalised with a high overhead allocation if overhead is allocated on labour hours — because the automated product actually consumes more machine-related overhead (depreciation, maintenance, energy) than a labour-intensive product. A more accurate approach is activity-based costing (ABC): identify the main overhead cost drivers (machine hours, quality inspection time, setups) and allocate each overhead pool based on the driver most relevant to it. For most SMB factories, a simplified ABC with two or three overhead pools is sufficient to capture the material distortions that a single blanket rate misses.
How to Calculate Your Overhead Rate#
The process for calculating an overhead allocation rate: (1) total your annual factory overhead cost from your Xero accounts — rent, rates, utilities, indirect labour, depreciation, maintenance, insurance, consumables. (2) Determine your annual direct labour hours or machine hours available (the allocation base). For a factory with 10 direct operators working 1,800 hours per year each, the base is 18,000 direct labour hours. (3) Divide total overhead by total hours: if overhead is £360,000 and the base is 18,000 hours, the overhead rate is £20 per direct labour hour. (4) Multiply each product's direct labour time per unit by this rate to get the overhead charge per unit. Update this rate at least annually — more frequently if your cost structure changes significantly. A rate calculated three years ago is likely significantly wrong today given energy and labour cost inflation.
How AskBiz and Xero Build Your True Cost Picture#
AskBiz production batch tracking captures actual direct materials issued and direct labour time per batch. When synced to Xero, these costs post to the correct accounts by batch and product. Xero's reporting then allows you to see direct material and direct labour cost per product line based on actuals. The overhead layer is configured in your Xero cost model: the overhead rate calculated above is applied to production hours recorded in AskBiz, adding the overhead component to each batch cost automatically. The result is a fully loaded unit cost report by product — direct materials + direct labour + overhead — in Xero, updated with each production batch rather than requiring a quarterly spreadsheet exercise. This real-time cost reporting is the management information that allows you to identify underpriced products, compare cost trends over time, and respond to cost changes (such as energy price increases) before they erode margin undetected.
Contribution Margin Analysis: When Full Cost Is Not the Only Lens#
While true unit cost including overhead is essential for long-term pricing decisions, contribution margin analysis is useful for short-term production decisions. Contribution margin = selling price − direct materials − direct labour (i.e., excluding overhead). Any product with a positive contribution margin is contributing to overhead recovery and should be produced, even if it does not fully cover overhead allocation in a slack capacity period. This distinction matters when making decisions about taking marginal orders, pricing for off-peak capacity, or responding to a competitive price challenge. Understanding the difference between full cost pricing (for sustainable long-term profitability) and contribution pricing (for short-term capacity utilisation decisions) is a fundamental manufacturing finance skill that prevents both over-pricing (refusing orders that would contribute to overhead) and under-pricing (accepting orders at below full cost as a permanent strategy).
Before and After: A Singapore Electronics Manufacturer#
A Singapore EMS company with 60 employees had been using a single 30% overhead rate applied to direct material cost — a rule-of-thumb approach that was never formally validated. When they rebuilt their cost model using AskBiz batch data synced to Xero, the true overhead rate (calculated on direct labour hours) was 42% of revenue — significantly higher than the 30% applied. More importantly, the analysis revealed that one product family — power conversion units requiring high-frequency test equipment — had three times the machine-related overhead intensity of their standard assemblies. Under the old rate, power conversion units were allocated less overhead than they should have been and were being quoted below true cost. Repricing these units using the corrected overhead model increased quoted prices by 11–16%. The customer accepted the increases with one exception, where the company chose to exit the product rather than continue at an uneconomic price.
Know Your True Cost Before You Price#
Every pricing decision you make — new customer quote, annual price review, response to a competitor's challenge — should be grounded in accurate unit cost including overhead. Without that foundation, you are pricing by instinct, and instinct consistently underestimates overhead because overhead is diffuse and indirect. Building an accurate cost model takes one to two days of effort the first time and much less to maintain thereafter, particularly when AskBiz and Xero are providing the underlying data automatically. The cost of one pricing error — winning a contract at below-cost pricing — typically exceeds the entire effort of building a proper cost model. Do the work once; benefit from it every time you price. AskBiz tracks your production costs in real time. Try free at askbiz.co
People also ask
How do I calculate the full cost of manufacturing a product?
True unit manufacturing cost has three components. First, direct materials: every raw material and bought-in component in the BOM, at current purchase price, adjusted for yield loss. This should be the most accurately tracked element in most factories.
What is overhead allocation in manufacturing costing?
The most common overhead allocation basis in SMB manufacturing is direct labour hours — overhead is spread across products in proportion to the direct labour hours each product consumes. This is reasonable when labour intensity drives most overhead consumption.
How do I calculate an overhead rate per direct labour hour?
The process for calculating an overhead allocation rate: (1) total your annual factory overhead cost from your Xero accounts — rent, rates, utilities, indirect labour, depreciation, maintenance, insurance, consumables.
What is the difference between full cost and contribution margin?
AskBiz production batch tracking captures actual direct materials issued and direct labour time per batch. When synced to Xero, these costs post to the correct accounts by batch and product.
How do I track overhead costs by product in Xero?
While true unit cost including overhead is essential for long-term pricing decisions, contribution margin analysis is useful for short-term production decisions. Contribution margin = selling price − direct materials − direct labour (i.e., excluding overhead).
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