The cost of making a product is more than its components and the direct hours on it. There is also overhead, the cost of running the plant. Getting overhead into product cost is what makes costing complete. This piece is about allocating manufacturing overhead in Odoo.
What manufacturing overhead is
Manufacturing overhead is the cost of running the manufacturing operation that is not a specific component in a product or a specific person's direct hour on it. It includes things like the cost of the facility, the cost of equipment beyond its direct running, supervision and support, utilities, and the many indirect costs of keeping a plant operating. Overhead is real cost, it is genuinely part of what it costs to make things, but unlike a component or a direct labour hour, it is not naturally attached to a particular product. That is what makes it a question: how does overhead, which is not tied to any one product, become part of each product's cost?
Why overhead has to reach product cost
Overhead has to be allocated into product cost because, if it is not, product costing is incomplete. A product costed at only its components and its direct operations, with no overhead, is undercosted: it is missing a genuine portion of what it cost to make. A manufacturer that costs products without overhead believes its products cost less than they really do, and prices and judges margin on that understatement. Allocating overhead into product cost is what makes the costed figure the full cost rather than a partial one.
How overhead reaches product cost in Odoo
The main practical route for getting overhead into product cost in Odoo is through the work center cost rates. A work center has a cost rate, and that rate should reflect the full, loaded cost of running the work center, which means it should include not only the direct cost but an appropriate share of overhead. When the work center rate carries overhead, then every operation that runs at that work center, and is costed at that rate, carries its share of overhead into the product. The product's operation cost is then a fully loaded cost, overhead included, rather than a bare direct cost.
So allocating manufacturing overhead in Odoo is, in large part, the discipline of setting work center cost rates that genuinely include overhead, rather than rates that reflect only the most obvious direct cost. A manufacturer that sets work center rates as fully loaded rates has built overhead allocation into its costing.
Allocating overhead sensibly
Allocating overhead means deciding how the total overhead is shared across the work centers, and through them across the products. This is a judgement, and it should be a sensible one: overhead should be allocated to work centers, and so to products, in a way that reflects, as fairly as possible, how the products actually draw on the plant's overhead. There is no single perfect formula, but the aim is fairness: a product that uses more of the plant's resources should carry more overhead, and the allocation basis should reflect that. A manufacturer should think about how its overhead genuinely relates to its production, and allocate accordingly, rather than spreading overhead arbitrarily.
Keep it proportionate
One honest note. Overhead allocation can be made extremely elaborate, and for most manufacturers, it should not be. The goal is product costs that include a fair, reasonable share of overhead, so the costed figure is genuinely complete. An allocation that is sensible and consistent achieves that. Chasing a theoretically perfect allocation through endless refinement adds effort without much improving the decisions the cost figures inform. A manufacturer should allocate overhead carefully enough to be fair and complete, and no more elaborately than that.
The takeaway
Manufacturing overhead is the real but indirect cost of running a plant, and it has to be allocated into product cost or costing is incomplete and products are undercosted. In Odoo, the main route is the work center cost rates: set them as fully loaded rates that include a fair share of overhead, and every operation costed at those rates carries overhead into the product. Allocate overhead sensibly, reflecting how products genuinely draw on the plant, and keep the allocation proportionate rather than elaborate. For how we approach Odoo for manufacturers, see our manufacturing work.