Which refers to the amount received by a firm from the sale of a given quantity of a commodity in the market?

What Is Quantity Demanded?

Quantity demanded is a term used in economics to describe the total amount of a good or service that consumers demand over a given interval of time. It depends on the price of a good or service in a marketplace, regardless of whether that market is in equilibrium.

The relationship between the quantity demanded and the price is known as the demand curve, or simply the demand. The degree to which the quantity demanded changes with respect to price is called the elasticity of demand.

Key Takeaways

• In economics, quantity demanded refers to the total amount of a good or service that consumers demand over a given period of time.
• Quantity demanded depends on the price of a good or service in a marketplace.
• The price of a product and the quantity demand for that product have an inverse relationship, according to the law of demand.

Quantity Demanded

Understanding Quantity Demanded

Inverse Relationship of Price and Demand

The price of a good or service in a marketplace determines the quantity that consumers demand. Assuming that non-price factors are removed from the equation, a higher price results in a lower quantity demanded and a lower price results in higher quantity demanded. Thus, the price of a product and the quantity demanded for that product have an inverse relationship, as stated in the law of demand.

An inverse relationship means that higher prices result in lower quantity demand and lower prices result in higher quantity demand.

Change in Quantity Demanded

A change in quantity demanded refers to a change in the specific quantity of a product that buyers are willing and able to buy. This change in quantity demanded is caused by a change in the price.

Increase in Quantity Demanded

An increase in quantity demanded is caused by a decrease in the price of the product (and vice versa). A demand curve illustrates the quantity demanded and any price offered on the market. A change in quantity demanded is represented as a movement along a demand curve. The proportion that quantity demanded changes relative to a change in price is known as the elasticity of demand and is related to the slope of the demand curve.

An Example of Quantity Demanded

Say, for example, at the price of $5 per hot dog, consumers buy two hot dogs per day; the quantity demanded is two. If vendors decide to increase the price of a hot dog to $6, then consumers only purchase one hot dog per day. On a graph, the quantity demanded moves leftward from two to one when the price rises from $5 to $6. If, however, the price of a hot dog decreases to $4, then customers want to consume three hot dogs: the quantity demanded moves rightward from two to three when the price falls from $5 to $4. 

By graphing these combinations of price and quantity demanded, we can construct a demand curve connecting the three points.

Using a standard demand curve, each combination of price and quantity demanded is depicted as a point on the downward sloping line, with the price of hot dogs on the y-axis and the quantity of hot dogs on the x-axis. This means that as price decreases, the quantity demanded increases. Any change or movement to quantity demanded is involved as a movement of the point along the demand curve and not a shift in the demand curve itself. As long as consumers' preferences and other factors don't change, the demand curve effectively remains static.

Price changes change the quantity demanded; changes in consumer preferences change the demand curve. If, for example, environmentally conscious consumers switch from gas cars to electric cars, the demand curve for traditional cars would inherently shift.

Price Elasticity of Demand

The proportion to which the quantity demanded changes with respect to price is called elasticity of demand. A good or service that is highly elastic means the quantity demanded varies widely at different price points.

Conversely, a good or service that is inelastic is one with a quantity demanded that remains relatively static at varying price points. An example of an inelastic good is insulin. Regardless of price point, those who need insulin demand it at the same amount.

What Is a Producer Surplus?

Producer surplus is the difference between how much a person would be willing to accept for a given quantity of a good versus how much they can receive by selling the good at the market price. The difference or surplus amount is the benefit the producer receives for selling the good in the market.

A producer surplus is generated by market prices in excess of the lowest price producers would otherwise be willing to accept for their goods. This may relate to Walras' law.

Key Takeaways

• Producer surplus is the total amount that a producer benefits from producing and selling a quantity of a good at the market price.
• The total revenue that a producer receives from selling their goods minus the marginal cost of production equals the producer surplus.
• Producer surplus plus consumer surplus represents the total economic benefit to everyone in the market from participating in production and trade of the good.

Producer Surplus

Understanding Producer Surplus

A producer surplus is shown graphically below as the area above the producer's supply curve that it receives at the price point (P(i)), forming a triangular area on the graph. The producer’s sales revenue from selling Q(i) units of the good is represented as the area of the rectangle formed by the axes and the red lines, and is equal to the product of Q(i) times the price of each unit, P(i).

Because the supply curve represents the marginal cost of producing each unit of the good, the producer’s total cost of producing Q(i) units of the good is the sum of the marginal cost of each unit from 0 to Q(i) and is represented by the area of the triangle under the supply curve from 0 to Q(i).

Subtracting the producer’s total cost (the triangle under the supply curve) from his total revenue (the rectangle) shows the producer’s total benefit (or producer surplus) as the area of the triangle between P(i) and the supply curve.

The Formula for Producer Surplus Is:

Total revenue - marginal cost = producer surplus

The size of the producer surplus and its triangular depiction on the graph increases as the market price for the good increases, and decreases as the market price for the good decreases.

Special Considerations

Producers would not sell products if they could not get at least the marginal cost to produce those products. The supply curve as depicted in the graph above represents the marginal cost curve for the producer.

From an economics standpoint, marginal cost includes opportunity cost. In essence, an opportunity cost is a cost of not doing something different, such as producing a separate item. The producer surplus is the difference between the price received for a product and the marginal cost to produce it.

Because marginal cost is low for the first units of the good produced, the producer gains the most from producing these units to sell at the market price. Each additional unit costs more to produce because more and more resources must be withdrawn from alternative uses, so the marginal cost increases and the net producer surplus for each additional unit is lower and lower.

Producer Surplus vs. Profit

Profit is a closely-related concept to producer surplus; however, they differ slightly. Economic profit takes revenues and subtracts both fixed and variable costs. Producer surplus, on the other hand, only takes off variable (marginal) costs.

Consumer Surplus and Producer Surplus

A producer surplus combined with a consumer surplus equals overall economic surplus or the benefit provided by producers and consumers interacting in a free market as opposed to one with price controls or quotas. If a producer could price discriminate correctly, or charge every consumer the maximum price the consumer is willing to pay, then the producer could capture the entire economic surplus. In other words, producer surplus would equal overall economic surplus.

However, the existence of producer surplus does not mean there is an absence of a consumer surplus. The idea behind a free market that sets a price for a good is that both consumers and producers can benefit, with consumer surplus and producer surplus generating greater overall economic welfare. Market prices can change materially due to consumers, producers, a combination of the two, or other outside forces. As a result, profits and producer surplus may change materially due to market prices.

Producer Surplus Example

Say that there are 20 companies that make widgets, each producing them at slightly different costs. ranging from $2.50 to $3.50 per widget. In the market, there is an equilibrium point where the amount of widgets supplied meets demand at $3.00.

The producer surplus would define those producers who can make widgets for less than $3.00 (down to $2.50), while those whose costs are up to $3.50 will experience a loss instead. For the lowest-cost producer, they would enjoy a surplus of $0.50 per widget.

How Do You Measure Producer Surplus?

With supply and demand graphs used by economists, the producer surplus would be equal to the triangular area formed above the supply line over to the market price. It can be calculated as the total revenue less the marginal cost of production.

What Is Producer Surplus Simply Put?

Put simply, the producer surplus is the difference between the price that companies are willing to sell products for and the prices that they actually get for them. 

What Is Total Surplus?

What refers to the amount earned by the firm from the sale of given quantity of a commodity in the market at various prices?

What refers to quantity of commodities offered for sale at a given price and time?

What is the of commodity available for sale?

Is the total quantity of commodity?