Cost Accounting Standard 2 (CAS-2): Capacity Determination

Cost Accounting Standard 2 (CAS-2) is about capacity determination. It explains how an entity should determine the capacity of a facility that produces goods or provides services, so costs can be assigned and absorbed on a consistent basis.

This page is about CAS-2 specifically. For the broader overview, see our guide to cost accounting standards. For the related overhead standard, see Cost Accounting Standard 3.

What does CAS-2 cover?

CAS-2 deals with the principles and methods used to classify and determine capacity. The official ICMAI standard frames capacity determination as part of ascertaining the cost of a product or service and presenting that information in cost statements.

In plain English, CAS-2 helps answer questions such as:

• What is the facility capable of producing or servicing?
• What capacity level should be used for cost absorption?
• How should normal downtime, practical constraints and actual use be reflected?
• What capacity information should be disclosed in cost statements?

Why capacity determination matters

Capacity affects how fixed and semi-fixed costs are absorbed. If capacity is overstated, unit costs may look artificially low. If capacity is understated, unit costs may look too high. Either error can distort pricing, profitability analysis, inventory valuation, contract costing and performance reporting.

That is why CAS-2 sits close to overhead allocation. Capacity is one of the foundations used when assigning production or operation overheads to products, services or cost objects.

Key capacity terms in CAS-2

The exact definitions should always be checked against the current ICMAI text, but the practical concepts are:

• Installed capacity: the maximum productive capability based on the facility, equipment or service setup.
• Practical capacity: installed capacity adjusted for unavoidable interruptions and practical operating limits.
• Normal capacity: the level expected over a period under normal circumstances, after considering demand, maintenance and operating conditions.
• Actual capacity utilisation: the capacity actually used during the period.
• Idle capacity: capacity that exists but is not used.

CAS-2 and overhead absorption

Capacity determination matters because overheads are often absorbed using a capacity base. For example, fixed production overhead may be spread across normal capacity rather than only actual output. That prevents abnormal low utilisation from loading too much fixed cost into each unit.

This also helps management separate operating efficiency from market demand or downtime issues. A facility may have high installed capacity but lower normal capacity because of realistic operating constraints. CAS-2 gives a structured way to document that difference.

Example: why capacity changes unit cost

Suppose fixed production overhead is GBP 120,000. If normal capacity is 60,000 units, the fixed overhead absorption rate is GBP 2 per unit. If the business incorrectly uses 40,000 units as the capacity base, the rate becomes GBP 3 per unit. That single capacity assumption changes product cost and may affect pricing, margin analysis and stock valuation.

The point of CAS-2 is not the arithmetic alone. It is the discipline of using a reasonable, consistent and disclosed capacity basis.

What should be disclosed?

Capacity-related disclosures usually help readers understand the basis used, changes from the previous period, and the reasons for under-utilisation or abnormal capacity effects. Useful disclosures include:

• the basis used to determine capacity;
• installed, practical, normal and actual capacity where relevant;
• changes in capacity and the reasons for those changes;
• treatment of idle capacity or abnormal costs;
• whether capacity is measured in units, hours or another appropriate measure.

CAS-2 vs the broad cost accounting standard topic

CAS-2 should not be treated as a generic page for every cost accounting standard. It has a specific job: capacity determination. The broader topic includes cost classification, allocation, standard costing, compliance frameworks and other standards. That broad topic belongs on the cost accounting standards keeper page.

Common mistakes when applying CAS-2

The most frequent error in applying CAS-2 is conflating installed capacity with practical capacity when calculating the capacity utilisation factor used for overhead absorption. Installed capacity is a theoretical maximum that ignores planned maintenance, changeovers and normal operating constraints — using it directly in an absorption rate calculation systematically understates the cost per unit during normal operations, because it spreads fixed overheads across a volume the business will never actually achieve. Practical capacity, which nets off unavoidable downtime, gives a more realistic denominator and is what CAS-2 expects to see used for standard costing and variance analysis.

A second common issue is failing to re-assess capacity when the underlying production process changes — for example, after new machinery is installed or a shift pattern changes. CAS-2 disclosure expectations extend to explaining the basis of capacity determination, so a stale capacity figure that no longer reflects actual operating conditions is both a costing accuracy problem and a disclosure compliance gap.

For this reason, it's good practice to revisit the capacity determination basis at least annually, or whenever there's a material change to plant, equipment or shift structure, rather than treating it as a one-off calculation set at initial standard costing.

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