Product Costing in Manufacturing: Standard Cost Explained

Product costing in manufacturing answers a question every factory owner should be able to answer instantly: what does it cost us to make one unit of this product? Surprisingly often, the answer is a rough estimate based on raw material plus a percentage, set years ago and never revisited. That is how manufacturers end up with products that look profitable but lose money once power, machine time, rejection and setup are counted. This guide explains how to build a product cost from material, labour and overheads, how to compute machine hour rates, the difference between standard and actual costing, with a worked cost sheet in rupees, and how to use costing for pricing and decisions.

The elements of product cost

Element	Includes	How it is traced
Direct material	Raw materials and bought-out components in the BOM, including normal scrap	BOM quantity x material rate
Direct labour	Wages of operators directly working on the product	Standard time x labour rate
Direct expenses	Job work charges, special tooling, royalties per unit	Per unit or per batch
Production overheads	Power, maintenance, depreciation of machines, supervision, consumables, factory rent	Absorbed via machine hours, labour hours or units
Administration and selling overheads	Office, sales, distribution	Usually kept out of inventory cost; added for pricing

For inventory valuation under AS 2, cost of conversion includes direct labour and a systematic allocation of fixed and variable production overheads, with fixed overheads allocated based on normal capacity. Administrative and selling overheads are excluded from inventory. For pricing, you need the full cost including them.

Step 1: Material cost from the BOM

Suppose a hypothetical Rajkot manufacturer makes a cast iron pump body. The BOM per unit:

Material	Qty per unit	Scrap allowance	Gross qty	Rate (₹)	Cost (₹)
Grey iron casting (kg)	8.5	4%	8.84	95	839.80
Bush (bought out)	1	0%	1	65	65.00
Fasteners set	1	2%	1.02	40	40.80
Paint (litre)	0.12	10%	0.132	320	42.24
Total material					987.84

Use landed material rates (including freight inward and non-creditable duties, excluding recoverable GST).

Step 2: Machine hour rates for overheads

In machine-intensive production, overheads are best absorbed using machine hour rates. For each work centre, add up annual costs and divide by normal productive hours.

Example: CNC machining centre

Annual cost item	₹
Depreciation of machine	4,20,000
Power (machine kW x hours x tariff)	3,60,000
Maintenance and spares	1,50,000
Tooling and consumables	2,40,000
Share of supervision and factory overheads	2,30,000
Total	14,00,000

Normal capacity: 2 shifts x 8 hours x 300 days = 4,800 hours, of which 80 percent is productive (setups, breakdowns and idle time excluded) = 3,840 hours. Machine hour rate = ₹14,00,000 / 3,840 = ₹364.58 per hour, before operator wages.

Using normal capacity rather than actual hours is important. If the machine runs only 2,500 hours in a slow year, the unabsorbed overhead is a period cost, not something loaded onto each unit, which would make products look more expensive exactly when you need to price competitively.

Step 3: Labour and routing

The routing lists operations, work centres and standard times. For the pump body:

Operation	Work centre	Time per unit (min)	Machine rate (₹/hr)	Labour rate (₹/hr)	Cost (₹)
Rough machining	VTL	18	300	180	144.00
Finish machining	CNC	24	364.58	200	225.83
Drilling and tapping	Radial drill	10	120	160	46.67
Testing and painting	Assembly bay	12	80	160	48.00
Total conversion		64			464.50

Each line is time in hours x (machine rate + labour rate). For finish machining: 0.4 hr x (364.58 + 200) = ₹225.83.

Add setup cost spread over batch size. If CNC setup takes 90 minutes and batches are 60 units, setup adds 1.5 hr x ₹564.58 / 60 = ₹14.11 per unit. Halve the batch size and setup cost per unit doubles, which is why small orders need different pricing.

Step 4: The complete cost sheet

Cost element	₹ per unit
Direct material	987.84
Conversion (labour + machine overheads)	464.50
Setup (batch of 60)	14.11
Rejection allowance at final inspection (2%)	29.33
Factory cost (inventory cost)	1,495.78
Administration overheads (8% of factory cost)	119.66
Selling and distribution (6% of factory cost)	89.75
Total cost	1,705.19

If the customer's price is ₹1,850, the margin is ₹144.81, about 7.8 percent of the selling price. If the sales team had been using "material plus 40 percent" (₹1,383) as cost, they believed the margin was about 25 percent of the selling price.

Standard costing vs actual costing

Aspect	Standard costing	Actual costing
What it is	Predetermined cost per unit, set for a period	Cost computed from actual consumption and expenses
Use	Pricing, budgeting, inventory valuation (if close to actual), variance analysis	Job costing, custom orders, final profitability
Strength	Variances highlight inefficiency quickly	Reflects reality for each job
Weakness	Becomes misleading if not updated	Known only after the job; harder to compare

Most manufacturers benefit from standard costs reviewed at least annually (and when material prices shift sharply), combined with actual cost tracking on work orders. The gap between the two shows where to act. Variance analysis is covered in our guide to budget vs actual variance analysis.

Using product costs for decisions

• Pricing: set minimum prices from full cost and target margin; for marginal orders, use contribution (price minus variable cost).
• Make or buy: compare the bought-out price with the variable cost of making, plus any fixed costs that would genuinely be avoided.
• Product rationalisation: products with low contribution per machine hour on a bottleneck machine should be repriced or deprioritised.
• Batch size decisions: quantify setup costs to set minimum order quantities.

A brief note on activity-based costing

Traditional costing spreads overheads using machine hours or labour hours. That works when overheads are driven by production volume. But some costs are driven by activities: the number of setups, purchase orders, quality inspections, engineering changes or customer-specific packaging. A low-volume, high-variety product may consume far more of these activities than its machine hours suggest.

Activity-based costing (ABC) identifies such activities, assigns their costs to activity pools, and charges products based on how many times they use each activity. A full ABC system is rarely needed in an SMB, but a light version helps: identify two or three major activity costs (setups, inspections, special packing) and assign them directly to the products that cause them. Often this reveals that small custom orders, which look profitable under volume-based costing, are actually subsidised by large standard orders.

Keeping costs current in an ERP

A cost sheet built once in Excel goes stale within months. Linking costing to live data keeps it useful:

• BOM and routing in the system: standard cost rolls up automatically from current BOM quantities, material rates and work centre rates.
• Work orders capture actuals: material issued, output, scrap and time booked against each order give actual cost per batch.
• Variance reports: standard vs actual by work order shows which products, machines or shifts drive the gap.
• Periodic cost roll: update standards on a defined date (for example, quarterly), so pricing and inventory use consistent figures.

The discipline that matters most is recording material issues and production output promptly. Costing cannot be more accurate than the shop floor data behind it.

Costing for quotations and new products

Many SMB manufacturers quote for new parts or custom orders. A quick costing routine before quoting avoids underpricing:

1. Estimate the BOM from the drawing, with material grades, weights and scrap.
2. Estimate the routing: which machines, setup times and cycle times, based on similar existing parts.
3. Apply current material rates and work centre rates.
4. Add tooling or fixture costs, amortised over the expected order quantity.
5. Add packing, freight and payment term costs.
6. Apply the target margin, and record the estimate so it can be compared with actual cost after the first batch.

Common costing mistakes

• Using a single plant-wide overhead percentage on material, which over-costs material-heavy products and under-costs machine-heavy ones.
• Ignoring scrap and rejection allowances.
• Absorbing overheads on actual hours in a slow period, inflating unit costs.
• Using outdated material rates after significant price movement.
• Not including setup time for small batches.
• Mixing GST into material costs when credit is available.

Frequently Asked Questions

What is standard cost in manufacturing?

A predetermined cost per unit, based on standard material quantities and prices, standard times and overhead rates. Actual results are compared with standards to identify variances.

How do you calculate a machine hour rate?

Add the annual costs of running the machine (depreciation, power, maintenance, tooling and a share of overheads) and divide by normal productive hours for the year.

Should administration overheads be included in inventory valuation?

No. Under AS 2, administrative overheads that do not contribute to bringing inventories to their present location and condition, and selling costs, are excluded from inventory cost. Include them in total cost for pricing.

How often should standard costs be updated?

At least once a year, and whenever key material prices or processes change significantly.

What is the difference between job costing and process costing?

Job costing tracks costs for each distinct order or batch, suiting engineering and custom manufacturing. Process costing averages costs over continuous production, suiting chemicals, food and textiles.

How Fininvo Helps

Fininvo's manufacturing module lists BOMs, routing and operations, work orders and production cost tracking, connected to inventory and accounting. See pricing for plans.