What Is Elastic Demand? Formula, Curve, and Examples

When the Amount Bought Is Very Sensitive to Price

Elastic Demand
A perfectly elastic demand curve is horizontal because a imperceptible change in price will create an infinite change in demand.

Elastic demand is when price or other factors have a big effect on the quantity consumers want to buy. You'll see it most often when consumers respond to price changes. If the price goes down just a little, they'll buy a lot more. If prices rise just a bit, they'll stop buying as much and wait for them to return to normal. Price is one of the five determinants of demand

If a good or service has elastic demand, it means consumers will do a lot of comparison shopping.

They typically do this when they aren't desperate to have it or they don't need it every day. They'll also comparison shop when there are a lot of other similar choices. 

The law of demand guides the relationship between price and the quantity bought. It states that the quantity purchased has an inverse relationship with price. When prices rise, people buy less. The elasticity of demand tells you how much the amount bought decreases when the price increases.

Other Types

There are two other types of demand elasticity. They also measure how much the quantity purchased changes when the price does.

  1. Inelastic demand is when the quantity demanded changes less than the price does.
  2. Unit elastic demand is when the quantity demanded changes the same percent that the price does.

Formula

The formula for elastic demand is the percent change in quantity demanded divided by the percent change in price. 

Elastic demand is when the percent change in the quantity demanded exceeds the percent change in price.

That makes the ratio more than one. For example, say the quantity demanded rose 10 percent when the price fell 5 percent. The ratio is 0.10/0.05 = 2.00.

Perfectly elastic demand is when the quantity demanded skyrockets to infinity when the price drops any amount. That, of course, could not happen in real life.

But many commodities approach that situation because they are highly competitive. The price is really the only thing that matters.

For example, two stores sell identical ounces of gold. One sells it for $1,800 an ounce while the other one sells it for $1,799 an ounce. With perfectly elastic demand, no one would buy the more expensive gold. Instead, they all buy gold from the less expensive dealer sells. In the real-life situation of almost perfect elasticity, many people will choose the cheaper gold over the more expensive, rather than all people. Some might buy the more expensive gold because they like the shop owner better.

Inelastic demand is when the quantity demanded rises by a lower percent than the price drops. For example, the quantity might rise 2 percent when the price fell 5 percent. That ratio is .02/.05 = .40, or less than one.

Unit elastic demand is when the quantity demanded changes the same percent as the change in price. In that case, the ratio is one. For example, the quantity demanded increased 5 percent in response to a price drop of 5 percent. The ratio is .05/.05 = 1. The price was a negative move while the quantity was a positive move. But there’s no need to include the minus sign since everyone knows that demand moves inversely to price.

Elastic Demand Curve

The demand curve is an easy way to determine if demand is elastic. The quantity demanded will change much more than the price. As a result, the curve will look lower and flatter than the unit elastic curve, which is a diagonal. The more elastic the demand, the flatter the curve. The graphic above shows the perfectly horizontal line of a perfectly elastic demand curve. 

The demand curve is based on the demand schedule. This table describes exactly how many units will be bought at each price.

Price is one of the five factors that determine demand.  There's a sixth, number of buyers, that drives aggregate demand. The important thing to know is that the demand curve only shows how the quantity changes in response to price, ceteris paribus (all other things being equal). If one of the other determinants change, it will shift the entire demand curve.

That means more (or less) will be demanded, even though the price remains the same.

Examples

A good example of elastic demand is housing. That's because there are so many different housing choices.  People could live in a townhouse, condo, apartment or even with friends or family. Because there are so many options, it’s easy for people to not pay more than they want to. 

Clothing also has elastic demand. True, people have to wear clothes, but there are many choices of what kind of clothing and how much to spend. When some stores offer sales, other stores have to lower their clothing prices to maintain demand. Small stores that can't offer huge discounts go out of business. During the Great Recession, many clothing stores were replaced by second-hand stores that offered quality used clothing at steeply discounted prices.