Fundamentals of Business Economics and Management · Theory of Demand and Supply

Meaning and Determinants of Demand Explained

Updated 10 October 2026 · Fact-checked

Demand is the quantity of a good that a consumer is willing and able to buy at a given price in a given period. It depends on price, income, prices of related goods, tastes, expectations and population. To solve questions, identify whether price or a non-price factor changed, then decide the movement or shift.

Understand Meaning and Determinants of Demand

In economics, demand is not just a wish to buy. It needs three things together: willingness to buy, ability to pay, and a stated price and time period. A student who wants a ₹80,000 laptop but has no money has a desire, not demand.

The demand schedule is a table showing the quantity a consumer buys at different prices. For example, at ₹10 per cup of tea you may buy 1 cup, at ₹8 you may buy 2, and at ₹6 you may buy 3. When you plot these pairs on a graph with price on the vertical axis and quantity on the horizontal axis, you get the demand curve. It normally slopes downward from left to right.

Individual demand is the demand of one consumer for a good. Market demand is the sum of the demands of all consumers in the market at each price. To get it from a schedule, add the quantities of all buyers at the same price. This is a horizontal summation of the individual demand curves.

The quantity demanded depends on several determinants: the price of the good itself, consumer income, prices of related goods (substitutes and complements), tastes and preferences, expectations about future prices and income, and the number of consumers (population). The price of the good itself moves you along the curve. All other factors shift the whole curve.

For income, goods are of two kinds. For a normal good, demand rises when income rises. For an inferior good, demand falls when income rises, as people switch to better alternatives. For related goods, if the price of tea rises, demand for coffee (a substitute) tends to rise. If the price of cars rises, demand for petrol (a complement) tends to fall.

Key formulas to remember

Demand function: Dx = f(Px, Py, Y, T, E, N); Px = own price, Py = price of related goods, Y = income, T = tastes, E = expectations, N = number of buyers. Other factors are held constant.
Market demand: Market demand at a price = Σ individual demands at that price; Add quantities at the same price, not prices.
Linear demand function: Q = a − bP; a is the quantity demanded at zero price; b shows the fall in quantity for a ₹1 rise in price.
Movement vs shift: Own price changes → movement along the curve; any other determinant changes → shift of the curve; A rise in demand shifts the curve right; a fall shifts it left.

How to solve Meaning and Determinants of Demand questions

Use this method for most MCQs on the meaning and determinants of demand.

1Read the question and find which variable has changed: own price or something else.
2If own price changed, decide it is a movement along the same demand curve (extension or contraction).
3If another factor changed (income, tastes, related goods, expectations, population), decide it is a shift of the curve (increase or decrease in demand).
4For related goods, first classify them as substitutes or complements. Substitutes: price and demand move in the same direction. Complements: they move in opposite directions.
5For income, classify the good as normal or inferior before deciding the direction.
6For market demand sums, add quantities across buyers at each price.
7Check the answer against the options and eliminate any that confuse movement with shift.

Quickest way: Own price or other factor?

When to use it: Use this for any conceptual MCQ asking what happens to demand or quantity demanded after a change.

Ask: did the good's own price change? If yes, the answer is a movement along the curve.
If no, the answer is a shift. Decide the direction using the factor.
Substitute price up: demand up. Complement price up: demand down.
Income up: normal good demand up, inferior good demand down.
For market demand, just add quantities at the same price.

Common mistakes in Meaning and Determinants of Demand

Treating a price fall as an increase in demand.
The words quantity demanded and demand sound the same.
Fix: A price change only changes quantity demanded (a movement). Demand changes only when a non-price factor changes.
Confusing substitutes with complements.
Students learn the terms but not the direction of the effect.
Fix: Substitutes can replace each other, so demand moves with the other good's price. Complements are used together, so demand moves against it.
Saying demand for every good rises with income.
Students forget inferior goods.
Fix: Check whether the good is normal or inferior. For inferior goods, higher income reduces demand.
Adding prices instead of quantities to get market demand.
Rushing through the schedule table.
Fix: Fix a price, then add each buyer's quantity at that price.
Calling a mere wish to buy demand.
The everyday meaning of demand is used.
Fix: Remember the three parts: willingness, ability to pay, and a price within a time period.

Worked examples

Example 1

At a price of ₹20 per kg, Ravi buys 4 kg of apples and Meena buys 6 kg. At ₹20 these are the only two buyers in the market. What is the market demand at ₹20?

Show the solution

Market demand is the sum of individual demands at the same price.
Ravi's demand at ₹20 = 4 kg.
Meena's demand at ₹20 = 6 kg.
Market demand = 4 + 6 = 10 kg.

Answer: 10 kg

Example 2

The price of tea rises from ₹10 to ₹12 per cup. As a result, the demand for coffee rises at every price. Which statement is correct? (A) Movement along the coffee demand curve (B) Rightward shift of the coffee demand curve (C) Leftward shift of the coffee demand curve (D) Movement along the tea demand curve only

Show the solution

The price that changed is the price of tea, not coffee.
For coffee, this is a change in a non-price factor (price of a related good).
Tea and coffee are substitutes, so a rise in the price of tea raises demand for coffee.
A rise in demand at every price means the coffee demand curve shifts right.
Option (A) is wrong because coffee's own price did not change. Option (C) is the wrong direction.

Answer: (B) Rightward shift of the coffee demand curve

Exam tips

Most questions test the difference between a movement along the curve and a shift. Decide this first.
Learn the list of determinants with one example each, as options often use real goods like tea, coffee, petrol and cars.
For inferior goods, expect an income question that reverses the usual direction.
Market demand questions use small numbers. Add quantities at the same price and check you used the right price row.
There is no negative marking, so attempt every question and eliminate wrong options first.

Practice questions from Theory of Demand and Supply

Meaning and Determinants of Demand in other exams

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

Meaning and Determinants of Demand: frequently asked questions

What is the difference between individual demand and market demand?

Individual demand is the quantity one consumer buys at each price. Market demand is the total of all consumers' quantities at each price. You get it by adding quantities across buyers.

What is a demand schedule and a demand curve?

A demand schedule is a table of prices and the quantities demanded at those prices. A demand curve is its graph, with price on the vertical axis and quantity on the horizontal axis. It normally slopes downward.

What are the main determinants of demand?

The main determinants are the price of the good, consumer income, prices of related goods, tastes and preferences, expectations of future prices and income, and the number of consumers. Only the good's own price causes a movement along the curve. The rest shift it.

What is an inferior good?

An inferior good is one whose demand falls when consumer income rises. People shift to better substitutes as they earn more. Which goods are inferior depends on the consumer and context.