A garment costing sheet can look accurate at first glance and still underestimate the actual cost of making a product. One common reason is that the costing team uses the garment's SMV but ignores the efficiency at which the sewing line is expected to operate.
In garment manufacturing, CM (Cost of Making) is commonly used to estimate the conversion cost of producing a garment. The exact scope of CM varies by factory. Some cost sheets include only sewing-related conversion costs, while others allocate additional cutting, finishing or overhead costs.
For a useful calculation, the factory must define its cost base clearly and use the same minute and manpower basis when calculating efficiency.
What Is SMV in Garment Costing?
SMV means Standard Minute Value. It represents the standard time assigned to an operation or garment, expressed in minutes.
A garment's SMV is normally built from its individual operations, such as shoulder joining, sleeve setting, side seam, collar attachment, hemming and other construction steps.
The Industrial Engineering team generally prepares or validates these time values through work study or an approved predetermined time system. The total garment SMV is then used for production planning, capacity analysis, line balancing and costing.
You can review the Textile Mates SMV Calculator to understand how observed cycle times, performance rating and allowances are used in a standard-minute calculation.
What Is Cost Per Minute (CPM)?
Cost per minute converts the factory's allocated production cost into a cost for each minute of production capacity.
Depending on the factory's costing policy, the monthly cost base may include:
- Operator wages and benefits
- Helper and support labour allocation
- Line supervision
- Maintenance and mechanical support
- Utilities and production-related overhead
- Other approved costs allocated to the production department
Fabric, trims, printing, washing and other order-specific material or process costs should be treated according to the factory's costing structure. They should not be added to CM automatically if they are already calculated in separate cost-sheet sections.
Available Production Minutes
First, calculate the total available minutes for the manpower group used in the costing model.
Available Minutes = Number of Operators × Working Days × Net Working Minutes per Day
Net working minutes should follow the factory's approved attendance and costing convention. Do not mix paid shift time with actual production time without defining the basis.
When cost per minute is based on available minutes:
CPM = Monthly Allocated Line Cost ÷ Available Minutes
How to Calculate Line Efficiency
Line efficiency compares the standard minutes earned from actual production with the minutes available from the defined manpower group.
Line Efficiency (%) = (Actual Output × Garment SMV) ÷ Available Minutes × 100
For example, a line with 40 operators works 480 net minutes per day. Its available minutes are:
40 × 480 = 19,200 minutes
If the garment SMV is 12.5 minutes and the line produces 1,152 pieces:
Earned minutes = 1,152 × 12.5 = 14,400 minutes
Efficiency = (14,400 ÷ 19,200) × 100
Line efficiency = 75%
Garment CM Cost Formula
When CPM is calculated using available minutes, the efficiency adjustment is required.
CM per Piece = SMV × CPM ÷ Efficiency (as a decimal)
For percentage input, use:
CM per Piece = SMV × CPM ÷ (Efficiency % ÷ 100)
For example, 60% efficiency must be entered as 0.60 in the first formula.
Practical CM Cost Calculation in BDT
Consider the following illustrative sewing-line information:
- Monthly allocated line cost: BDT 1,000,000
- Direct sewing operators: 40
- Working days: 26
- Net working minutes per day: 480
- Garment SMV: 12.5 minutes
- Expected line efficiency: 60%
Step 1: Calculate available minutes
Available minutes = 40 × 26 × 480
Available minutes = 499,200
Step 2: Calculate cost per minute
CPM = 1,000,000 ÷ 499,200
CPM = BDT 2.0032 per available minute
Step 3: Calculate CM per garment
CM = 12.5 × 2.0032 ÷ 0.60
CM = approximately BDT 41.73 per piece
This is an illustrative calculation, not a market rate or a recommended CM quotation. The monthly line cost and the scope of the included expenses must come from the factory's actual costing records.
How Efficiency Changes CM Cost
Assume the SMV, monthly cost and available minutes remain unchanged. Only the expected efficiency changes.
| Efficiency | CM per Piece (BDT) |
|---|---|
| 60% | 41.73 |
| 65% | 38.52 |
| 70% | 35.77 |
The figures show why the assumed efficiency matters during costing. A lower efficiency means more available production minutes are needed to earn the standard minutes required for the garment.
However, the costing team should not simply select the highest possible efficiency to make a quotation look competitive. The expected efficiency should reflect style complexity, order size, learning curve, line layout, operator skill and the factory's production history.
An Important CPM Difference That Can Cause Double Counting
Factories may use different definitions of cost per minute. This is where costing errors can occur.
Method A: CPM based on available minutes
CPM = Monthly line cost ÷ Available minutes
CM = SMV × CPM ÷ Efficiency
Method B: Cost per earned minute
Cost per earned minute = Monthly line cost ÷ Earned standard minutes
CM = SMV × Cost per earned minute
Both methods can produce the same result when the same cost base and minute basis are used consistently. But if CPM has already been calculated using earned minutes, dividing by efficiency again will overstate CM.
What Should Be Checked Before Approving a CM Rate?
- Confirm that the garment SMV is based on the approved construction and operation bulletin.
- Check whether the cost-per-minute figure uses available or earned minutes.
- Use the same manpower basis in CPM and line efficiency calculations.
- Include the correct monthly cost allocation.
- Use a realistic efficiency assumption for the order and style.
- Keep fabric, trims, wash, print and other separate costs from being counted twice.
- Review the final CM against the factory's approved costing policy.
After calculating the making cost, the Garment Cost Calculator can help bring together fabric, trims, CM and other cost components in a broader garment costing estimate.
You can also explore the Textile Mates Calculator Hub for related tools used in SMV, line efficiency, capacity, fabric consumption and garment costing.
Frequently Asked Questions
What does CM mean in garments?
CM commonly means Cost of Making. It is the conversion cost assigned to producing a garment, but its exact included activities and overheads depend on the factory's costing policy.
What is the formula for CM cost per piece?
When CPM is based on available minutes, CM per piece = SMV × CPM ÷ efficiency as a decimal. If the CPM is already based on earned minutes, multiply SMV by that earned-minute cost without applying efficiency again.
Is SMV the same as SAM?
SMV means Standard Minute Value and SAM means Standard Allowed Minutes. In many garment factories, the terms are used for the standard time assigned to an operation or garment. Follow the terminology and method used in the factory's approved system.
Does higher efficiency reduce CM cost?
With the same SMV and cost base, a higher achieved efficiency reduces the cost per standard minute when CPM is based on available minutes. The efficiency assumption must still be realistic.
Does CM include fabric and trims?
Not automatically. Many cost sheets calculate fabric, trims and processing separately from CM. Check the factory's cost-sheet structure to avoid missing or double-counting expenses.
Conclusion
Garment CM costing is not just a multiplication of SMV by a cost-per-minute figure. The calculation must also reflect how the factory defines available minutes, earned minutes and production efficiency.
When the costing basis is consistent, the result becomes more useful for order evaluation, price negotiation, production planning and factory cost control. The most important step is to use verified SMV, actual cost records and a realistic efficiency assumption.
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