Supply
Supply shows how much producers will sell at each price.
About this topic
Supply is the quantity of a good that producers are willing and able to sell at each price. The law of supply says that as price rises, quantity supplied rises, so the supply curve slopes upward, as higher prices make production more profitable and encourage firms to bring more to market. A price change moves along the curve; non-price factors shift the whole curve.
Firms respond to prices because costs rise as output grows. Producing extra units often needs overtime pay or less suitable land, so a firm needs a higher price to make it worthwhile. Supply matters because it is the other half of the market, deciding with demand what is produced and sold.
Factors that shift supply include costs of inputs such as wages and raw materials, technology, taxes and subsidies, the number of sellers, expectations and natural events. For example, if a drought ruins the wheat harvest, farmers can supply less at every price, so the curve shifts left and bread becomes dearer. If a new machine cuts the cost of making shoes, supply shifts right and shoes become cheaper.
Common mistakes: confusing a shift with a movement along the curve, and thinking a firm will always supply more simply because it wants to; it must also be able to. Tip: a cost-cutting change shifts supply right, a cost increase shifts it left.
Key ideas
- Law of supply: higher price, more supplied
- Supply curve slopes up
- Costs and technology shift supply
Quick check
Use cases: where Supply helps
- Homework: review the key idea behind Supply before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Supply without notes.
- Visual learning: play with the interactive lab to see how Supply changes when you adjust its inputs.
- Teaching a friend: explain Supply in your own words, then compare your version with the key ideas.
Economics explains prices, jobs, budgets and government policy in daily life.
Frequently asked questions
What is Supply?
Supply shows how much producers will sell at each price.
What will I learn in Supply?
Law of supply: higher price, more supplied. Supply curve slopes up. Costs and technology shift supply.
Is Supply part of Economics & Money?
Yes. It is one of 30 Economics & Money topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Supply lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Supply?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.