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Fundamentals of Financial and Cost Accounting · Classification of Costs (CAS 1)

Normal and Abnormal Costs: Meaning, Difference and Treatment

Updated 10 October 2026 · Fact-checked

A normal cost is incurred under normal operating conditions at a given activity level and is part of the cost of the product. An abnormal cost is an unusual, avoidable cost beyond normal levels. It is not added to product cost and is charged to the Costing Profit and Loss Account.

Understand Normal and Abnormal Costs

Every production process has some cost you expect. A factory expects a little material to be lost in cutting, some time to be lost in changing shifts, and some machine wear. These are normal costs. They arise under normal operating conditions, at a normal level of activity, and they are part of the cost of the good output.

Sometimes something unusual happens. A fire destroys stock, a machine breaks down because of poor maintenance, or a worker spoils a batch by carelessness. The extra cost caused by such events is an abnormal cost. It is not expected and is generally avoidable or not part of regular operations.

The key idea is treatment. Normal costs are absorbed by good units, so they raise the cost per unit. Abnormal costs are kept out of product cost. They are written off to the Costing Profit and Loss Account, so they do not distort the cost of the product or the selling price quoted to customers.

Why do this? Management wants to know the true cost of making a unit. If unusual losses are loaded into product cost, costs look higher than they should be, and the inefficiency stays hidden. Showing abnormal loss separately points management to the problem.

For losses in material or units, a normal loss is a loss expected in the process, and an abnormal loss is any loss above it. Its value is worked out on the same basis as good output, using cost per unit based on normal output.

Key formulas to remember

Treatment of normal cost
Normal cost → included in the cost of good production
It raises the cost per good unit.
Treatment of abnormal cost
Abnormal cost → written off to Costing Profit and Loss Account
It is not included in product cost or stock valuation.
Cost per unit with normal loss
Cost per unit = (Total cost − Scrap value of normal loss) ÷ (Input units − Normal loss units)
Divide by expected good output, not by actual output.
Abnormal loss units
Abnormal loss = Actual loss units − Normal loss units
Use this only when actual loss is more than normal loss.
Value of abnormal loss
Abnormal loss cost = Abnormal loss units × Cost per unit, less any scrap value realised on those units
The net amount is transferred to the Costing Profit and Loss Account.

How to solve Normal and Abnormal Costs questions

Use this method for any question that asks you to classify a cost or treat a loss.

  1. 1Read the situation and ask: is this expected under normal operating conditions, or is it unusual?
  2. 2If it is a regular, expected part of operations, call it a normal cost and include it in product cost.
  3. 3If it comes from an unusual event such as fire, theft, accident, breakdown or negligence, call it an abnormal cost.
  4. 4For unit losses, find normal loss as a given percentage of input, then compare it with actual loss.
  5. 5Compute cost per unit using total cost, less scrap value of normal loss, divided by input minus normal loss units.
  6. 6Value abnormal loss units at that cost per unit, then deduct any scrap value realised on them.
  7. 7Transfer the abnormal amount to the Costing Profit and Loss Account and keep it out of product cost.

Quickest way: Normal or abnormal in ten seconds

When to use it: Use this for MCQs that ask you to classify a cost or say where it is charged.

  1. Look for words like fire, theft, strike, negligence or breakdown. These signal abnormal.
  2. Look for words like usual, inherent, expected or within the allowed percentage. These signal normal.
  3. Remember: normal goes into product cost, abnormal goes to Costing Profit and Loss Account.
  4. In numerical MCQs, compute only normal loss units, good output, cost per unit, and abnormal loss units. Skip full account preparation.
  5. Eliminate any option that adds abnormal loss to product cost or stock value.

Common mistakes in Normal and Abnormal Costs

  • Adding abnormal loss to the cost of good units

    Students treat all losses the same way.

    Fix: Only normal loss is absorbed by good units. Abnormal loss goes to the Costing Profit and Loss Account.

  • Dividing total cost by actual output to get cost per unit

    It looks simpler and seems logical.

    Fix: Divide by input minus normal loss units, which is expected good output.

  • Forgetting scrap value of normal loss

    Students focus on the loss units only.

    Fix: Deduct the scrap value of normal loss from total cost before computing the cost per unit.

  • Calling a loss abnormal when it is within the normal percentage

    Students see any loss as a problem.

    Fix: Abnormal loss exists only if actual loss exceeds normal loss. If actual loss is less, the difference is abnormal gain.

  • Treating abnormal cost as a product cost because it is a real expense

    Students confuse being a real expense with being part of product cost.

    Fix: It is a real expense, but it is excluded from product cost and charged to the Costing Profit and Loss Account.

Worked examples

Example 1

A process takes 1,000 units of input at a total cost of ₹50,000. Normal loss is 10% of input and has no scrap value. Actual output is 850 units. Find the cost per unit and the value of abnormal loss.

Show the solution
  1. Normal loss = 10% × 1,000 = 100 units.
  2. Expected good output = 1,000 − 100 = 900 units.
  3. Cost per unit = ₹50,000 ÷ 900 = ₹55.56 approximately.
  4. Actual loss = 1,000 − 850 = 150 units.
  5. Abnormal loss = 150 − 100 = 50 units.
  6. Value of abnormal loss = 50 × ₹50,000 ÷ 900 = ₹2,500,000 ÷ 900 = ₹2,777.78 ≈ ₹2,778.

Answer: Cost per unit is about ₹55.56 and abnormal loss is 50 units worth about ₹2,778, charged to the Costing Profit and Loss Account.

Example 2

A process takes 2,000 units of input at a total cost of ₹1,80,000. Normal loss is 5% of input, sold as scrap at ₹10 per unit. Actual output is 1,850 units. Find the cost per unit and the value of abnormal loss after scrap.

Show the solution
  1. Normal loss = 5% × 2,000 = 100 units.
  2. Scrap value of normal loss = 100 × ₹10 = ₹1,000.
  3. Expected good output = 2,000 − 100 = 1,900 units.
  4. Cost per unit = (₹1,80,000 − ₹1,000) ÷ 1,900 = ₹1,79,000 ÷ 1,900 = ₹94.21 approximately.
  5. Actual loss = 2,000 − 1,850 = 150 units, so abnormal loss = 150 − 100 = 50 units.
  6. Cost of abnormal loss = 50 × ₹94.21 = ₹4,711 approximately.
  7. Scrap realised on abnormal loss = 50 × ₹10 = ₹500.
  8. Net abnormal loss = ₹4,711 − ₹500 = ₹4,211 approximately.

Answer: Cost per unit is about ₹94.21 and net abnormal loss is about ₹4,211, transferred to the Costing Profit and Loss Account.

Exam tips

  • Questions often give a short case such as a fire loss or machine breakdown. Decide normal or abnormal first, then pick the treatment.
  • In numerical MCQs, divide by good output, not by input. This is the most common trap.
  • Check whether scrap value is given. If it is, subtract it for normal loss before finding cost per unit.
  • Eliminate options that put abnormal loss into stock valuation or product cost.

Practice questions from Classification of Costs (CAS 1)

Normal and Abnormal Costs in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Normal and Abnormal Costs: frequently asked questions

What is the difference between normal and abnormal cost?

A normal cost is expected under normal operating conditions and is included in product cost. An abnormal cost is unusual and avoidable, and is charged to the Costing Profit and Loss Account instead.

How is abnormal loss treated in cost accounting?

Abnormal loss is valued at the cost per unit of good output, less any scrap value realised. The net amount is written off to the Costing Profit and Loss Account and is not added to product cost.

Can you give examples of abnormal costs?

Loss of stock by fire or theft, idle time due to a strike, and spoilage caused by negligence are common examples. They are outside the regular running of the process.

Is normal loss included in the cost of good units?

Yes. The cost of normal loss, after deducting any scrap value, is spread over the good units. That is why cost per unit is found by dividing by expected good output.