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

Historical, Standard and Estimated Cost with Cost Centre and Cost Unit

Updated 10 October 2026 · Fact-checked

Costs can be classified by when they are determined. Historical cost is the actual cost after it is incurred. Estimated cost is predicted before production. Standard cost is a carefully set target cost under defined conditions. A cost centre is a location or function where costs are collected. A cost unit is the unit of product or service to which costs are related.

Understand Cost Concepts: Historical, Standard, Estimated and Cost Unit

Start with one question: when is the cost known? Under CAS 1, costs can be classified by the time of determination. This gives three groups: historical, estimated and standard costs.

Historical cost (also called actual cost) is the cost that has really been incurred. You know it only after production or service is done. If a bakery spent ₹48,000 to make 1,200 cakes last month, ₹48,000 is the historical cost. It is accurate, but it comes too late to control that month's spending.

Estimated cost is a prediction made before the work is done. It is based on past records and expected changes in prices and conditions. Firms use it for quotations, tenders and fixing prices. It is a forecast, so it can differ from the actual cost. Standard cost is also set in advance, but it is different. It is a scientifically set target for efficient working under stated conditions. The firm compares actual cost with it to find variances. Estimated cost says what the cost is likely to be. Standard cost says what the cost should be.

Now the other terms. A cost centre is a location, person, function or item of equipment for which costs are collected and then related to cost units. Examples are a machine shop, a canteen or a sales department. A cost unit is the unit of product, service or time to which costs are related, such as a tonne of steel, a kilometre of transport or a patient-day in a hospital. A cost object is anything for which cost is measured, such as a product, a service, a department or a project. A cost unit is one kind of cost object.

Keep the link simple. Costs are first collected at cost centres. They are then charged to cost units. The cost object is the wider idea that covers both.

Key formulas to remember

Historical cost: Historical cost = Actual cost incurred (known after the event); Also called actual cost. It is ascertained after production or service is completed.
Estimated cost: Estimated cost = Predicted cost (set before the event, based on past data and expected changes); Used for quotations, tenders and pricing. It is a forecast and can differ from actual.
Standard cost: Standard cost = Predetermined target cost under defined efficient conditions; Used for control. Variance = Actual cost − Standard cost.
Cost centre vs cost unit: Cost centre = where cost is collected; Cost unit = what cost is measured per; Cost centre is a place, person or function. Cost unit is a measure of output.
Cost per unit: Cost per unit = Total cost ÷ Number of cost units; The cost unit must be the one that suits the industry, such as tonne, kWh or passenger-km.

How to solve Cost Concepts: Historical, Standard, Estimated and Cost Unit questions

Most questions in this topic ask you to identify a term or match it with an example. Use the same method each time.

1Read the statement and look for a time clue: after the event, before the event, or a target.
2If the cost is actual and known only after work is done, choose historical cost.
3If it is a forecast used for a quote or tender, choose estimated cost.
4If it is a target set under efficient conditions and used to find variances, choose standard cost.
5If the question names a place, department or machine where costs are gathered, choose cost centre.
6If the question names a measure of output such as a tonne, a kilometre or a bed-day, choose cost unit.
7If the wording is wide, such as any product, service, activity or project, choose cost object.
8For numerical questions, divide total cost by the number of cost units and check that the unit is correct.

Quickest way: Time and place test

When to use it: Use it for one-line identification and matching MCQs where four terms look alike.

Ask: after, before or target? After means historical. Before means estimated. Target means standard.
Ask: place or measure? A place or function is a cost centre. A measure of output is a cost unit.
If an option says cost object, check whether the item is something cost is being measured for.
Remove options that mix up forecast with target.
For per-unit sums, divide and then check the answer against the options.

Common mistakes in Cost Concepts: Historical, Standard, Estimated and Cost Unit

Treating estimated cost and standard cost as the same thing.
Both are fixed before production, so they look alike.
Fix: Estimated cost is a forecast of what cost is likely to be. Standard cost is a target of what cost should be, and it is used for variance analysis.
Saying historical cost is only the cost of old assets.
In financial accounting, historical cost means the original purchase price.
Fix: In cost accounting, historical cost means actual cost ascertained after it is incurred. Read the paper context.
Mixing up cost centre and cost unit.
Both are used to trace costs, and the names sound similar.
Fix: Cost centre is where cost is collected, such as the packing department. Cost unit is what is measured, such as one carton.
Choosing a wrong cost unit for the industry.
Students pick a familiar unit without thinking of the output.
Fix: Match the unit to the output: tonne for steel, kWh for electricity, passenger-km for transport, patient-day for hospitals.
Thinking a cost object must be a product.
Textbook examples mostly use products.
Fix: A cost object can be a product, service, department, customer or project. Anything for which cost is measured qualifies.

Worked examples

Example 1

A firm gives a tender quote for a job using expected material prices and labour rates before starting work. After finishing, the actual cost turns out to be ₹2,10,000, against the quote basis of ₹2,00,000. Name each cost and state the difference.

Show the solution

The cost used for the quote was set before the work and is a forecast. So ₹2,00,000 is the estimated cost.
The cost found after completion is the actual cost. So ₹2,10,000 is the historical cost.
Difference = ₹2,10,000 − ₹2,00,000 = ₹10,000.
Actual is higher than estimated, so the estimate was too low by ₹10,000.

Answer: ₹2,00,000 is the estimated cost and ₹2,10,000 is the historical cost. The actual cost exceeded the estimate by ₹10,000.

Example 2

A transport company spent ₹1,80,000 in a month. Its buses carried passengers for a total of 90,000 passenger-km. The maintenance workshop is one department of the company. Identify the cost centre and cost unit, and find the cost per unit.

Show the solution

The maintenance workshop is a department where costs are collected. So it is a cost centre.
The measure of output for transport is the passenger-km. So the cost unit is the passenger-km.
The cost per passenger-km is worked out on the company's total cost, not on the workshop alone.
Cost per unit = Total cost ÷ Number of cost units.
Cost per passenger-km = ₹1,80,000 ÷ 90,000 = ₹2.

Answer: The maintenance workshop is the cost centre. The cost unit is the passenger-km. The company's total cost works out to ₹2 per passenger-km.

Exam tips

Look for time words such as after, before, predetermined and target. They decide the answer in most MCQs.
Learn one industry example for each cost unit. Matching questions often ask this.
When two options are estimated and standard cost, ask which one is used for control and variances. That is standard cost.
Remember the order: cost centres collect costs, cost units absorb them, and cost object is the broader term.
There is no negative marking, so always attempt every question after eliminating the options you know are wrong.

Practice questions from Classification of Costs (CAS 1)

Cost Concepts: Historical, Standard, Estimated and Cost Unit in other exams

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

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Cost Concepts: Historical, Standard, Estimated and Cost Unit: frequently asked questions

What is the difference between estimated cost and standard cost?

Estimated cost is a forecast of what a cost is likely to be, based on past data and expected changes. Standard cost is a target of what the cost should be under efficient, defined conditions. Standard cost is used to measure variances.

What is the difference between a cost centre and a cost unit?

A cost centre is a place, person, function or equipment where costs are collected. A cost unit is the unit of output, such as a tonne or a kilometre, to which cost is related. One collects cost and the other measures it.

What is a cost object in cost accounting?

A cost object is anything for which cost is measured. It can be a product, a service, a department, a customer or a project. A cost unit is one type of cost object.

Is historical cost the same as actual cost?

In cost accounting, yes. Historical cost is the actual cost incurred and is known only after the event. It is useful for records but too late to control the spending.