Tracking materials, labor, and production costs is part of your day-to-day operations.
But how those costs come together determines whether your margins are actually accurate.
Cost of goods manufactured is not just an accounting exercise. It directly affects how you price products, evaluate profitability, and make decisions about production.
When the calculation is incomplete or applied too broadly, it can create a gap between what looks profitable on paper and what is actually driving margin in your business.
This comes down to how the calculation is built — and where it tends to break down
Key Takeaways
- COGM accuracy depends on more than materials and labor. Manufacturing overhead and WIP adjustments often have the biggest impact on true cost per unit.
- Overhead allocation should reflect how your plant operates today. Flat or outdated methods can distort margins across product lines.
- Total profitability can hide product-level issues. Reviewing cost by SKU helps identify which products are truly driving margin.
- Inconsistent WIP tracking can shift costs between periods. This makes it harder to evaluate performance and production efficiency accurately.
- When your cost data reflects reality, decisions get easier. When your COGM reflects reality, pricing, production planning, and margin analysis become more reliable.
The Big Picture of Cost of Goods Manufactured
Cost of goods manufactured (COGM) captures the total cost required to produce goods during a specific period.
It brings together three main cost drivers:
- Direct materials
- Direct labor
- Manufacturing overhead
This number is what ultimately feeds into your cost of goods sold and, in turn, your gross margin.
On paper, the calculation looks straightforward. The challenge is making sure each component reflects what’s actually happening on the floor.
The Cost of Goods Manufactured Formula
COGM starts with total production costs and adjusts for work in progress.
Start with your total manufacturing costs.
The base calculation:
Total Manufacturing Costs = Direct Materials Used + Direct Labor + Manufacturing Overhead
Direct materials used:
Direct Materials Used = Beginning Raw Materials + Purchases of Raw Materials – Ending Raw Materials Inventory.
Put together, the full COGM formula becomes:
COGM = Beginning WIP Inventory + Direct Materials Used + Direct Labor + Manufacturing Overhead – Ending WIP Inventory.
On paper, it’s clean. In practice, it depends on how accurate your inputs are.
Direct materials and labor are usually tracked closely. Overhead and WIP are where things tend to drift.
Where Costing Starts to Break Down
As your operation grows, your cost structure usually becomes more complex. New product lines are added, production processes evolve, and scheduling, staffing, and purchasing patterns shift.
The systems used to track cost don’t always change at the same pace.
Over time, that gap can create small inconsistencies in how you capture and apply costs, which makes the overall calculation less reliable than it appears.
Take a Second Look At Your Overhead
Materials and labor are visible and easy to tie to production. Overhead is different.
It includes things like supervision, utilities, equipment depreciation, maintenance, and facility costs. These costs are real, but they’re not always allocated consistently across products.
In some cases, overhead is estimated broadly or applied as a flat percentage that no longer reflects how the plant actually runs today. As production volumes, shift structures, or facility usage change, that approach can create gaps between actual cost and reported cost.
Even small differences in overhead allocation can have a noticeable impact on margin at the product level.
Consider a manufacturer producing two product lines:
- A high-volume standard item
- A lower-volume custom product.
Both products use similar materials and labor hours, so they appear to carry similar costs. Overhead is applied as a flat 15% of direct labor across all products.
On the surface, margins look consistent.
But in reality, the custom product requires more machine setup time, more supervision, and more frequent quality checks. It also runs in smaller batches, which increases downtime between runs.
Because overhead is applied evenly, those additional costs are not fully captured. The standard product ends up absorbing more overhead than it should, while the custom product appears more profitable than it actually is.
Evaluate Product-Level Performance
Another common pattern is focusing on overall profitability without breaking it down by product line or SKU.
It is not unusual for a small group of products to generate the majority of margin while others contribute very little or operate at a loss. But without SKU-level visibility, those differences are hard to detect.
Say for example, a manufacturer reviews monthly financials and sees steady performance. Revenue is growing, and overall gross margin holds at 32%.
At a high level, the business looks healthy.
However, once costs are broken down by product line, a different pattern emerges.
- One core product accounts for 60% of the total margin. It runs efficiently, turns quickly, and has stable input costs.
- A second product line generates modest margin but requires more labor variability.
- A third line, which was introduced to expand the product offering, is consistently underperforming. It requires more rework, has higher scrap rates, and ties up more production time than expected.
Because the business is only reviewing total profitability, that third product line continues to run without adjustment. Over time, it offsets gains from the stronger products.
Once the team isolates cost per SKU, they realize they need to either reprice the product, adjust the production process, or reconsider its role in the product mix.
Fully Capture Work in Progress Projects
Work in progress (WIP) plays an important role in the COGM calculation, but it is often one of the harder components to track accurately.
Production rarely starts and finishes neatly within a single reporting period. Materials are introduced, labor is applied, and overhead accumulates over time. If WIP isn’t measured consistently, the final cost calculation can shift from one period to the next.
This doesn’t always show up as a clear issue in your financials, but it can affect how you interpret changes in margin or production efficiency.
Say a manufacturer produces goods in multi-day batches. At the end of each month, several jobs are partially complete.
In one month, the team estimates that $150,000 of production is in progress and records that as ending WIP. The following month, a similar level of work is underway, but the estimate comes in at $110,000 due to differences in how production stages were evaluated.
Nothing about the actual production process changed significantly. The difference comes from how WIP was measured.
On paper, the changes may not raise immediate concern. But for the operations and finance teams trying to understand performance, the inconsistency makes it harder to determine whether margins are actually improving or simply shifting between periods.
What This Formula Means for Your Margins
When cost of goods manufactured is not fully aligned with production reality, the impact shows up in how you price, plan, and prioritize production.
- Pricing may be based on incomplete cost data.
- A product that appears profitable could be absorbing more overhead than expected.
- Another product may be priced aggressively without a clear understanding of its true cost structure.
Over time, this can lead to a situation where the business performs well overall, but certain product lines are not contributing the way you expect.
These shifts make it harder to catch margin issues early.
Strengthen Your Cost of Goods Manufactured Picture
Cost of goods manufactured connects what happens on the production floor to how your business performs.
When the calculation reflects materials, labor, and overhead accurately, you have a clearer view of your margins and a stronger basis for decision-making.
If it doesn’t, the numbers may look reasonable at a high level, but they’re harder to trust when you need to make decisions.
If your cost data doesn’t reflect how your operation actually runs, it may be time to take a closer look at how your reporting is structured, Duffy Kruspodin’s manufacturing and distribution team works with companies to make sure their cost data reflects how their operation actually runs.
Schedule a conversation with our team today.
General Disclosure: The information provided in this article is for general informational purposes only and does not constitute professional accounting, tax, or legal advice. Laws and regulations are subject to change and may vary based on specific facts or jurisdictions. Presentation of this information is not intended to create, and receipt does not constitute, an accountant-client relationship. Readers are advised not to act upon this information without seeking the services of a qualified professional.
