CBSE Class 12 Microeconomics Revision Notes Chapter 3 Production and Costs

Production is the process of transforming inputs such as labour, capital and raw materials into output. In Class 12 Microeconomics, this chapter explains production function, short run, long run, product curves, returns to scale and cost behaviour.

Production and Costs is an important chapter in Class 12 Microeconomics because it explains how firms produce output and manage costs. A firm uses inputs such as labour, machines, land and raw materials to produce goods or services. The cost of using these inputs affects the firm’s profit.

Use these CBSE Class 12 Microeconomics Revision Notes Chapter 3 for the 2026–27 academic year to revise production function, TP, AP, MP, law of variable proportions, returns to scale and cost concepts. These notes follow the chapter flow and keep formulas, curves and definitions easy to revise.

Key Takeaways

  • Production function: Shows the maximum output that can be produced from given inputs.
  • Short run: At least one factor remains fixed and one factor can vary.
  • Law of variable proportions: Marginal product first rises, then falls as more units of a variable factor are used.
  • Cost function: Shows the least cost of producing each level of output.

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Access Class 12 Microeconomics Chapter 3 Production and Costs Notes in 30 Minutes

Revise this chapter in two parts. First, study production concepts. Then revise cost concepts and curve relationships.

Revision Area What to Revise
Production Transformation of inputs into output
Production Function Relation between inputs and maximum output
Short Run At least one fixed factor
Long Run All factors can be varied
Isoquant Input combinations producing same output
TP, AP and MP Product measures of a variable input
Law of Variable Proportions Three stages of returns to a factor
Returns to Scale CRS, IRS and DRS
Cost Concepts Explicit, implicit and economic cost
Cost Curves TFC, TVC, TC, AFC, AVC, AC and MC

CBSE Class 12 Microeconomics revision infographic on production and costs with a factory and short-run cost curves.

Production and Costs Class 12 Notes: What This Chapter Covers

Production and Costs Class 12 Notes study the behaviour of a producer. A producer uses inputs to create output and pays for these inputs. The cost of production affects profit.

Production

Production means transforming resources into commodities or services.

Examples:

Producer Inputs Used Output Produced
Farmer Land, labour, seeds, water Wheat
Tailor Cloth, thread, machine, labour Shirts
Car manufacturer Factory, machinery, steel, labour Cars
Domestic helper Labour Cleaning services

Cost of Production

A firm has to pay for inputs used in production. This payment is called cost of production.

Examples of cost include wages, rent, raw material cost, interest and electricity charges.

Firm’s Objective

A firm earns revenue by selling output. Profit is the difference between revenue and cost.

Profit = Revenue - Cost

A firm generally aims to maximise profit.

Production Function in Class 12 Microeconomics Chapter 3 Notes

A production function shows the technical relationship between inputs and output.

Meaning of Production Function

The production function of a firm shows the maximum quantity of output that can be produced using different combinations of inputs.

It can be written as:

q = f(L, K)

Here:

Symbol Meaning
q Maximum output
L Labour
K Capital
f Functional relationship

A production function is defined for a given technology. If technology improves, the maximum output from the same inputs can increase.

Features of Production Function

Feature Explanation
Input-output relation Shows relation between factors and output
Maximum output Assumes efficient use of inputs
Given technology Based on current production technology
Physical concept Shows physical output, not cost or revenue
Firm-specific Can differ across firms and production methods

Short Run and Long Run

The difference between short run and long run depends on whether all inputs can be changed.

Short Run

Short run is a period in which at least one factor of production is fixed.

The firm can change output by changing only the variable factor.

Factor Type Meaning
Fixed Factor Cannot be changed in the short run
Variable Factor Can be changed in the short run

Example:
A firm may keep capital fixed and change labour to increase output.

Long Run

Long run is a period in which all factors of production can be changed.

In the long run, there is no fixed factor.

Basis Short Run Long Run
Fixed factor Exists Does not exist
Variable factor At least one All factors variable
Output change By changing variable factor By changing all factors
Main law Law of variable proportions Returns to scale

Isoquant

An isoquant is a curve that shows all possible combinations of two inputs that produce the same level of output.

For example, if 10 units of output can be produced with different combinations of labour and capital, all those combinations lie on the same isoquant.

Features of Isoquant

Feature Explanation
Same output Every point on an isoquant gives the same output
Two-input analysis Usually labour and capital are used
Downward sloping More of one input needs less of the other
Higher isoquant Shows higher level of output

Isoquants are useful because they show how a firm can substitute one input for another while keeping output constant.

Total Product, Average Product and Marginal Product

When one input is varied and all other inputs are kept constant, output changes. This gives total product, average product and marginal product.

Total Product

Total Product is the total output produced by using a given quantity of a variable input, while other inputs remain fixed.

It is also called total physical product.

Formula:

TP = Sum of marginal products

Average Product

Average Product is output per unit of variable input.

Formula:

AP = TP / Variable Input

If labour is the variable input:

APL = TPL / L

Marginal Product

Marginal Product is the change in total product due to the use of one additional unit of variable input.

Formula:

MP = Change in TP / Change in Variable Input

If labour changes by one unit:

MPn = TPn - TPn-1

Product Formula Table

Concept Formula
Total Product TP = Sum of MP
Average Product AP = TP / Variable Input
Marginal Product MP = Change in TP / Change in Variable Input
Marginal Product of nth unit MPn = TPn - TPn-1

Relationship Between TP, AP and MP

TP, AP and MP are closely connected.

TP Behaviour MP Behaviour
TP rises at an increasing rate MP rises
TP rises at a decreasing rate MP falls but remains positive
TP is maximum MP = 0
TP starts falling MP becomes negative

Relationship Between AP and MP

Situation Effect on AP
MP > AP AP rises
MP = AP AP is maximum
MP < AP AP falls

MP cuts AP at the maximum point of AP.

Curve Behaviour Notes

Curve Shape or Behaviour
TP Curve First rises at increasing rate, then at decreasing rate, then may fall
MP Curve Inverted U-shaped
AP Curve Inverted U-shaped
MP and AP MP cuts AP at AP’s maximum point

Law of Variable Proportions

The law of variable proportions explains how output changes when more units of one variable factor are used with fixed factors.

It states that when more units of a variable factor are combined with fixed factors, marginal product initially rises and then starts falling after a point.

This law applies in the short run.

Stages of Law of Variable Proportions

The law of variable proportions has three stages.

Stage I: Increasing Returns to a Factor

In Stage I, TP rises at an increasing rate and MP rises.

This happens because fixed factors are underutilised at the beginning. More units of the variable factor improve the use of fixed factors.

Reasons for increasing returns:

  • Underutilisation of fixed factors
  • Indivisibility of factors
  • Better efficiency of the variable factor

Stage II: Diminishing Returns to a Factor

In Stage II, TP rises at a decreasing rate and MP falls but remains positive.

This is the rational stage of production because total output is still increasing.

Reasons for diminishing returns:

  • Fixed factor starts becoming crowded
  • Variable factor has less fixed factor to work with
  • Factor proportion becomes less suitable

Stage III: Negative Returns to a Factor

In Stage III, TP falls and MP becomes negative.

This happens when too many units of the variable factor are used with fixed factors.

Reasons for negative returns:

  • Poor coordination between fixed and variable factors
  • Excessive use of fixed factors
  • Overcrowding of the variable factor

Three Stages Summary Table

Stage TP MP Main Feature
Stage I Rises at increasing rate Rises Increasing returns
Stage II Rises at decreasing rate Falls but positive Diminishing returns
Stage III Falls Negative Negative returns

Returns to Scale in Production and Costs

Returns to scale apply in the long run because all inputs can be changed.

Returns to scale show how output changes when all inputs are increased in the same proportion.

Constant Returns to Scale

Constant Returns to Scale means output increases in the same proportion as inputs.

If inputs double and output also doubles, it is CRS.

Increasing Returns to Scale

Increasing Returns to Scale means output increases by a larger proportion than inputs.

If inputs double and output more than doubles, it is IRS.

Decreasing Returns to Scale

Decreasing Returns to Scale means output increases by a smaller proportion than inputs.

If inputs double and output less than doubles, it is DRS.

Returns to Scale Table

Type Input Change Output Change
CRS Inputs increase by t times Output increases by t times
IRS Inputs increase by t times Output increases by more than t times
DRS Inputs increase by t times Output increases by less than t times

Cobb-Douglas Production Function

A Cobb-Douglas production function can be written as:

q = x1α x2β

Here:

Symbol Meaning
q Output
x1 Factor 1
x2 Factor 2
α, β Constants

If both inputs are increased t times, then output depends on α + β.

Condition Return to Scale
α + β = 1 Constant Returns to Scale
α + β > 1 Increasing Returns to Scale
α + β < 1 Decreasing Returns to Scale

Cost Concepts in Production and Costs

A firm uses inputs to produce output. The payment made for these inputs forms the cost of production.

Economic Cost

Economic cost is the sum of explicit cost and implicit cost.

Formula:

Economic Cost = Explicit Cost + Implicit Cost

Explicit Cost

Explicit cost is the actual money paid by a firm for hiring or buying inputs.

Examples:

  • Wages
  • Rent
  • Interest
  • Raw material cost
  • Electricity bill

These costs are recorded in books of accounts.

Implicit Cost

Implicit cost is the estimated cost of using self-owned resources.

Example:
If the owner uses their own building for production, the rent that could have been earned from that building is an implicit cost.

Normal Profit

Normal profit is the minimum return required to keep the entrepreneur in business.

It is treated as part of cost in economics.

Cost Concepts Table

Cost Type Meaning
Explicit Cost Actual money payment
Implicit Cost Estimated cost of self-owned resources
Economic Cost Explicit cost + implicit cost
Normal Profit Minimum return required by entrepreneur

Total Fixed Cost, Total Variable Cost and Total Cost

Short-run cost is divided into fixed cost and variable cost.

Total Fixed Cost

Total Fixed Cost is the cost incurred on fixed factors.

It remains constant at all levels of output.

Examples include rent, licence fees and interest on fixed capital.

Formula:

TFC = TC - TVC

or

TFC = AFC × Q

Features of TFC

  • TFC remains constant when output changes.
  • TFC exists even when output is zero.
  • The TFC curve is parallel to the X-axis.
  • At zero output, TC = TFC.

Total Variable Cost

Total Variable Cost is the cost incurred on variable factors.

It changes with output.

Examples include raw materials, power and wages of variable labour.

Formula:

TVC = TC - TFC

or

TVC = AVC × Q

Features of TVC

  • TVC is zero when output is zero.
  • TVC rises as output increases.
  • TVC first rises at a decreasing rate and later at an increasing rate.
  • The shape of TVC is linked with the law of variable proportions.

Total Cost

Total Cost is the sum of total fixed cost and total variable cost.

Formula:

TC = TFC + TVC

or

TC = AC × Q

Total Cost Summary Table

Cost Formula Behaviour
TFC TC - TVC Constant at all output levels
TVC TC - TFC Changes with output
TC TFC + TVC Increases as output increases

Average Cost and Marginal Cost

Average cost and marginal cost are per-unit cost concepts.

Average Fixed Cost

Average Fixed Cost is fixed cost per unit of output.

Formula:

AFC = TFC / Q

Features of AFC

  • AFC falls as output increases.
  • AFC curve is a rectangular hyperbola.
  • AFC never becomes zero.
  • AFC curve never touches the X-axis.

Average Variable Cost

Average Variable Cost is variable cost per unit of output.

Formula:

AVC = TVC / Q

AVC is generally U-shaped because of the law of variable proportions.

Average Cost

Average Cost is the total cost per unit of output.

Formula:

AC = TC / Q

or

AC = AFC + AVC

Marginal Cost

Marginal Cost is the change in total cost due to the production of one additional unit of output.

Formula:

MC = Change in TC / Change in Q

When output changes by one unit:

MCn = TCn - TCn-1

Since fixed cost does not change with output, marginal cost is also related to change in TVC.

MC = Change in TVC / Change in Q

Average and Marginal Cost Formula Table

Concept Formula
AFC TFC / Q
AVC TVC / Q
AC TC / Q
AC AFC + AVC
MC Change in TC / Change in Q
MCn TCn - TCn-1

Relationship Between MC, AVC and AC

Marginal cost affects both AVC and AC.

Relationship Between MC and AVC

Situation Result
MC < AVC AVC falls
MC = AVC AVC is minimum
MC > AVC AVC rises

MC cuts AVC at the minimum point of AVC.

Relationship Between MC and AC

Situation Result
MC < AC AC falls
MC = AC AC is minimum
MC > AC AC rises

MC cuts AC at the minimum point of AC.

Relationship Between AC and AVC

AC = AFC + AVC

The vertical distance between AC and AVC is AFC.

As output increases, AFC falls. So the distance between AC and AVC keeps reducing, but AC and AVC never meet because AFC never becomes zero.

Short Run Cost Curves

Cost curves show how costs behave as output changes.

Curve Behaviour
TFC Horizontal line parallel to X-axis
TVC Starts from origin and rises with output
TC Starts from TFC and rises with output
AFC Downward sloping rectangular hyperbola
AVC U-shaped
AC U-shaped
MC U-shaped and cuts AVC and AC at their minimum points

Important Cost Curve Points

  • TC and TVC remain parallel because TFC is constant.
  • TFC is the vertical distance between TC and TVC.
  • AC and AVC never intersect because AFC is always positive.
  • MC cuts AVC and AC at their lowest points.

Cost Function

A cost function shows the least cost of producing each level of output, given technology and input prices.

For each output level, a firm chooses the least expensive input combination.

This is why production and cost are connected. The firm studies how much output it can produce and how much cost it must incur.

Quick Revision Tables for Production and Costs

Production Formula Table

Concept Formula
Production Function q = f(L, K)
Average Product AP = TP / Variable Input
Marginal Product MP = Change in TP / Change in Variable Input
MP of nth unit MPn = TPn - TPn-1
Cobb-Douglas Function q = x1α x2β

Cost Formula Table

Concept Formula
Economic Cost Explicit Cost + Implicit Cost
TC TFC + TVC
TFC TC - TVC
TVC TC - TFC
AC TC / Q
AC AFC + AVC
AFC TFC / Q
AVC TVC / Q
MC Change in TC / Change in Q

Product Curve Relationship Table

Relationship Rule
TP rises faster MP rises
TP rises slower MP falls but remains positive
TP maximum MP = 0
TP falls MP negative
MP > AP AP rises
MP = AP AP maximum
MP < AP AP falls

Cost Curve Relationship Table

Relationship Rule
MC < AVC AVC falls
MC = AVC AVC minimum
MC > AVC AVC rises
MC < AC AC falls
MC = AC AC minimum
MC > AC AC rises

Important Terms in Production and Costs

Term Meaning
Production Transformation of inputs into output
Production Function Relation between inputs and maximum output
Fixed Factor Factor that cannot be changed in short run
Variable Factor Factor that can be changed in short run
Isoquant Input combinations giving same output
Total Product Total output from variable input
Average Product Output per unit of variable input
Marginal Product Additional output from one more unit of input
Law of Variable Proportions Output law when one input varies and others stay fixed
Returns to Scale Output response when all inputs change together
Explicit Cost Actual money payment
Implicit Cost Cost of self-owned resources
Normal Profit Minimum return needed by entrepreneur
Marginal Cost Additional cost of one more unit of output

Common Mistakes in Class 12 Microeconomics Chapter 3 Notes

Mistake Correct Point
Confusing short run with a fixed number of months Short run means at least one factor is fixed
Treating production function as cost function Production function shows output, cost function shows least cost
Assuming MP is always positive MP can become zero or negative
Saying AP is maximum when MP is zero AP is maximum when MP = AP
Forgetting TFC at zero output TFC exists even at zero output
Assuming AFC becomes zero AFC falls but never becomes zero
Mixing returns to factor and returns to scale Returns to factor is short run, returns to scale is long run

Useful Links for Class 12 Microeconomics

Section Useful Links
Revision Notes CBSE Class 12 Microeconomics Revision Notes
Microeconomics Notes CBSE Class 12 Microeconomics Revision Notes Chapter 1
Economics Notes CBSE Class 12 Economics Notes
NCERT Solutions NCERT Solutions Class 12 Microeconomics
NCERT Solutions NCERT Solutions Class 12 Economics
Syllabus CBSE Class 12 Economics Syllabus
Sample Papers CBSE Sample Papers for Class 12 Economics
Important Questions Important Questions Class 12 Microeconomics

FAQs (Frequently Asked Questions)

This chapter explains how firms use inputs to produce output and how production decisions create costs. It covers production function, short run, long run, product curves, returns to scale and cost curves.

Marginal product shows the additional output from one more unit of variable input. It helps explain the law of variable proportions and the shape of TP, AP and MP curves.

In the short run, at least one factor is fixed. In the long run, all factors can be changed. The law of variable proportions applies in the short run, while returns to scale apply in the long run.

AC and MC are U-shaped because of the law of variable proportions. Initially, increasing returns reduce per-unit cost. Later, diminishing returns increase per-unit cost.

When MC is less than AC, AC falls. When MC equals AC, AC is minimum. When MC is greater than AC, AC rises. MC cuts AC at its minimum point.