How to value manufacturing inventory
Raw materials, work-in-process, and finished goods each need their own cost logic. Get the rollup wrong and gross margin is wrong on every unit sold.
Why manufacturing inventory valuation is hard
Unlike a retailer buying and reselling a finished item, a manufacturer converts raw materials into finished goods through labor and overhead, and each stage - raw materials, work-in-process, finished goods - carries a different cost basis. Getting the bill-of-materials cost rollup wrong means every unit sold is mispriced against its real cost, and margin reporting is wrong at the product level even if the company total looks fine.
Where teams get it wrong
- Costing finished goods from a manual spreadsheet BOM instead of the live bill of materials.
- Not updating rolled-up cost when a component price changes, so margin reports use stale figures.
- Allocating overhead as a flat percentage instead of tying it to actual labor or machine hours.
- Losing track of work-in-process value between raw materials and finished goods.
- Reconciling inventory value to the general ledger only at year-end instead of every period.
The COGM Framework
- 1Maintain an explicit bill of materials for every finished good, listing every component and quantity.
- 2Roll up component costs plus direct labor plus allocated overhead into a per-unit standard cost.
- 3Recost the rollup automatically whenever a component price changes.
- 4Track work orders through release, materials issue, labor application, overhead application, and completion.
- 5Value work-in-process as the sum of costs applied to incomplete work orders.
- 6Calculate cost of goods manufactured for the period and reconcile finished-goods inventory to the ledger.
How Fintra values inventory for you
| Step | What Fintra does |
|---|---|
| Bill of materials | BOMs list every component and quantity for each finished good, explodable to full detail. |
| Cost rollup | BOM explode-and-cost-rollup recalculates per-unit standard cost from current component prices. |
| Work orders | Work orders track release, issue-materials, apply-labor, apply-overhead, and complete stages. |
| WIP value | WIP/COGM reports value work-in-process from costs applied to open work orders. |
| COGM | Cost of goods manufactured calculates per period from completed work orders. |
| Reconcile | The perpetual inventory stock ledger reconciles finished-goods value to the general ledger every period. |
Cost of goods manufactured
COGM = Beginning WIP Inventory + Total Manufacturing Costs (Materials + Labor + Overhead) − Ending WIP Inventory
COGM measures the cost of units completed during the period, distinct from cost of goods sold, which also accounts for the change in finished-goods inventory.
Your inventory valuation checklist
Set these up before your next physical count
- Maintain a current bill of materials for every finished good.
- Recost the BOM rollup whenever a component price changes.
- Define your overhead allocation basis explicitly - labor hours, machine hours, or units.
- Track work orders through every production stage, not just start and finish.
- Value work-in-process from actual costs applied, not an estimate.
- Calculate COGM every period, not just at year-end.
- Reconcile inventory value to the general ledger every close.
Frequently asked questions
What is a BOM cost rollup?
It is the calculation that sums the cost of every component, labor operation, and overhead allocation in a bill of materials to produce a per-unit standard cost for a finished good. When a component price changes, recosting the rollup updates the standard cost for every product that uses that component, which matters because a single common part can feed dozens of finished goods.
What is the difference between COGM and COGS?
Cost of goods manufactured (COGM) measures the cost of units completed during a period, accounting for the change in work-in-process inventory. Cost of goods sold (COGS) starts from COGM and adjusts for the change in finished-goods inventory, reflecting what was actually sold rather than what was produced. The two differ whenever production and sales volumes diverge in a period.
How should overhead be allocated to inventory cost?
Overhead should be allocated on a basis that reflects how it is actually consumed - commonly labor hours or machine hours - rather than a flat percentage of material cost. A flat-percentage allocation distorts the cost of labor-intensive versus material-intensive products, which then distorts margin reporting for each.
How often should manufacturing inventory be reconciled?
Every accounting period, not just at year-end or during a physical count. Reconciling the perpetual inventory ledger to the general ledger monthly catches costing errors, miscounted receipts, and stale BOM rollups while they are still a small variance rather than a large one discovered at annual audit.
Stay in the loop
One practical finance briefing a week - new guides, checklists, and benchmarks.
Keep inventory cost current, automatically
Fintra recosts your BOM rollup and reconciles WIP and COGM to the ledger every period. Free to start, no card required.
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