Production Possibility Curve (PPC): Graph, Examples and Shifts

The production possibility curve (PPC), also called the production possibilities frontier (PPF), is a graph of the largest combinations of two goods that an economy, a firm or a person can produce with the resources and technology it has now. Points on the curve are efficient, points inside it waste resources, and points outside it cannot be reached yet.

Question	Short answer
What does it show?	The most of one good you can make for each amount of the other
What is its slope?	Opportunity cost: what you give up to get one more unit of the other good
What shape is it?	Usually bowed out, because opportunity cost rises; it can also be straight or bowed in
What shifts it?	More or better resources, or new technology
What does not?	A recession (the point moves inside) or new prices or tastes (the point moves along)
Where is it taught?	AP Macro Topic 1.2, AP Micro Topic 1.3, CBSE Class XI Unit 4

Below: how to draw the curve and calculate opportunity cost from a table, why it bows out, what does and does not shift it, and a factory example in which the frontier comes straight from plant capacity.

What is the production possibility curve?

Three standard texts define it in similar terms. OpenStax Principles of Economics calls it “a diagram that shows the productively efficient combinations of two products that an economy can produce given the resources it has available.”

The College Board’s AP course framework calls the PPC “a model used to show the tradeoffs associated with allocating resources.” India’s NCERT textbook says the curve “gives the maximum amount of corn that can be produced in the economy for any given amount of cotton and vice-versa.”

One graph carries several ideas at once. The AP framework lists them: scarcity, opportunity cost, efficiency, underused resources, and economic growth or contraction.

Points on, inside and outside the curve

• On the curve: efficient. You cannot make more of one good without making less of the other. OpenStax calls this productive efficiency.
• Inside the curve: inefficient. The economy can produce this mix, but some resources are “underemployed or are utilised in a wasteful fashion” (NCERT). Khan Academy puts it plainly: “When an economy is in a recession, it is operating inside the PPC.”
• Outside the curve: unattainable. There are not enough resources, with today’s technology, to produce this mix. It comes within reach only if the curve itself moves out.

PPC, PPF and the other names

PPC and PPF mean the same thing. Khan Academy notes the curve is “sometimes called the production possibilities frontier (PPF)”, and NCERT uses only “production possibility frontier”. CORE Econ’s textbook The Economy 2.0 calls the boundary a “feasible frontier” and names its slope the marginal rate of transformation (MRT): “the quantity of a good that must be sacrificed to acquire one additional unit of another good.” MIT’s international trade course adds that this slope is “also the opportunity cost”.

How is the production possibilities curve drawn?

You draw a PPC from a production schedule: a table listing the most of one good that can be made for each amount of the other. The AP framework expects students to “draw an accurately labeled graph” and to “calculate (using data from PPCs or tables as appropriate) opportunity cost.” The table below is NCERT’s own example (Table 1.1): an economy that can grow corn, cotton, or a mix of the two.

Point	Corn	Cotton	Cotton given up for this unit of corn
A	0	10	None
B	1	9	1
C	2	7	2
D	3	4	3
E	4	0	4

1. Put one good on each axis and label both axes, with units.
2. Plot each row of the schedule as a point: A (0, 10) to E (4, 0).
3. Join the points. That line is the frontier, and every mix on or under it can be produced.
4. Read the opportunity cost off each step: how much of the vertical good falls for each extra unit of the horizontal good.

How to calculate opportunity cost from a PPC

Opportunity cost is always counted in the good you give up. Khan Academy’s rule: “opportunity costs are always expressed in terms of the good that is given up.” So the formula is:

Opportunity cost of one more unit of X = units of Y given up ÷ units of X gained

Moving from B to C in the table gains 1 unit of corn and gives up 9 − 7 = 2 units of cotton, so that unit of corn costs 2 cotton. The four steps cost 1, 2, 3 and 4 cotton: each extra unit of corn costs more than the last. Read in the other direction it works the same way. Going from E to D gains 4 cotton for 1 corn (0.25 corn each), while going from B to A gains only 1 cotton for 1 corn (1 corn each).

Watch the sign. A formula written as a change over a change gives a negative number when one good falls as the other rises. Report the cost as a positive amount of the good given up: “2 cotton”, not “−2”.

Why the curve bows outward

OpenStax names the reason “the law of increasing opportunity cost”, which “happens because some resources are better suited for producing certain goods and services instead of others.” In the corn and cotton example, the first units of corn can use the land best suited to corn, so little cotton is lost. The last units of corn need land and workers that are better at cotton, so each one costs more cotton. The Federal Reserve’s teaching video gives the same reason: “some resources are better suited for some tasks than others.”

You can see this happen in the factory example below. A textbook by Rittenberg and Tregarthen shows that even when each plant on its own has a straight-line frontier, “combining them according to comparative advantage” gives a curve “made up of linear segments.”

Can a PPC be a straight line, or bowed inward?

Yes to both. The AP framework says “the shape of the PPC depends on whether opportunity costs are constant, increasing, or decreasing”:

• Straight line: constant opportunity cost. Every unit of one good costs the same amount of the other. This happens when resources are equally good at both jobs. In the Federal Reserve’s example, each extra 2 widgets always costs 4 gadgets.
• Bowed out (concave to the origin): increasing opportunity cost. This is the usual case. The Federal Reserve video says the frontier “is usually drawn as a curved line that is concave to the origin.”
• Bowed in (convex to the origin): decreasing opportunity cost. MIT’s trade course says this is possible, for example when “the farmer could become more efficient, the more production is concentrated in a single crop”, but warns it “may not hold at a more aggregated level.”

A note on words: Khan Academy and the Federal Reserve video call the usual curve “concave”. One Federal Reserve lesson plan calls the same outward-curving shape “convex”. Both mean the bowed-out picture. If your course material uses one term, use that one.

Importance

The PPC sits in the opening unit of both AP Economics courses and of CBSE’s Class XI microeconomics, because it turns the basic problem of economics into a picture you can measure. Four uses stand out:

• It answers “what to produce”. NCERT lists three central problems of every economy: what to produce, how, and for whom. Choosing a point on the PPC is the first of them, including whether to make “consumption goods or … investment goods (like machine) which will boost production and consumption tomorrow.”
• It leads into growth. In AP Macroeconomics the PPC and the long-run aggregate supply curve “both represent maximum sustainable capacity”, and “an outward shift in the PPC is analogous to a rightward shift” of that supply curve.
• It explains trade. A country has a comparative advantage in the good it makes at a lower opportunity cost, which OpenStax stresses “is not the same as absolute advantage, which is when a country can produce more of a good.” OpenStax’s example: “The U.S. PPF is flatter than the Brazil PPF”, so wheat costs the U.S. less sugar cane. Specialising and trading then allows “consumption opportunities beyond the PPC” (AP).
• It works inside a firm. A plant with fixed capacity has its own frontier, and choosing the product mix is choosing a point on it. The factory example below shows how.

Production possibilities frontier example

Here is the corn and cotton schedule from the table above, drawn as a curve. The red steps are the opportunity costs: 1, 2, 3 and then 4 units of cotton for each extra unit of corn.

• A and E are the extremes: all resources in cotton (10 units) or all in corn (4 units).
• B, C and D are mixes on the frontier. All five points are efficient; none is “better” until you know what people want.
• U is inside the curve. The economy could have more of both goods by using idle resources.
• X is outside the curve. It needs more resources or better technology.

A factory example: Wyndor Glass, from plant capacity to frontier

The PPC is not only a classroom economy. Any plant with fixed capacity has one, and a product-mix plan is a choice of a point on it. A well-known teaching case is the Wyndor Glass Co. problem, the prototype example in Hillier and Lieberman’s Introduction to Operations Research (section 3.1). Wyndor makes glass doors and wood-framed windows in three plants. Aluminum frames are made in Plant 1, wood frames in Plant 2, and Plant 3 makes the glass and assembles both products. The data, as reproduced in ISEG Lisbon’s and Constructor University’s operations research course materials:

Plant	Hours per door batch	Hours per window batch	Hours available per week
Plant 1	1	0	4
Plant 2	0	2	12
Plant 3	3	2	18

From these limits we worked out the most windows Wyndor can make for each number of door batches. Plant 2 caps windows at 12 ÷ 2 = 6 batches. Plant 3 allows (18 − 3 × doors) ÷ 2. Plant 1 caps doors at 4. The frontier is the smaller of the two window limits at each door count:

Door batches	Most window batches	Windows given up for this door batch
0	6	None
1	6	0
2	6	0
3	4.5	1.5
4	3	1.5
5	Not possible	Plant 1 is full

Read it like any PPC. The first two door batches cost no windows at all, because Plant 3 still has spare hours while Plant 2 is the limit on windows. After that, Plant 3 is full and each door batch takes 3 of its hours, enough for 1.5 window batches, so each door batch costs 1.5 window batches. At 4 door batches Plant 1 is full and no amount of windows given up buys another door. The cost rises from 0 to 1.5 to “impossible”: the frontier bows out, built from straight segments, exactly as the Rittenberg and Tregarthen textbook describes.

Prices choose the point; they do not move the frontier. At $3,000 per door batch and $5,000 per window batch, the most profitable mix is 2 door batches and 6 window batches, $36,000 a week, the textbook’s answer. Comparing the corner points ourselves, if a window batch earned less than $2,000 (two thirds of a door batch’s $3,000) the best mix would jump to 4 doors and 3 windows. The plants, their hours and the frontier would not change at all; only the chosen point would. MIT’s lecture notes say the same of whole economies: the PPF is set “given technology and factor endowments”, and “movements along PPF represent a reallocation of the factors of production” when prices change.

Capacity and technology do move it. Working the same arithmetic: give Plant 3 six more hours a week (24 instead of 18) and every mix up to 4 doors and 6 windows becomes possible, an outward shift. Cut a door batch’s time in Plant 3 from 3 hours to 2 and the frontier grows only on the door side, to 4 doors with 5 windows instead of 3: a pivot, because the technology improved for one product. Lose 4 hours in Plant 2 and the window limit falls from 6 to 4 batches: an inward shift.

This is the everyday work behind capacity planning: Plant 3 is the bottleneck on the sloped part of the frontier, and the decision to add hours there is a decision to move the frontier. For checking a production plan against capacity, see rough-cut capacity planning.

A national example: guns and butter in the United States, 1939 to 1944

Paul Samuelson’s 1948 textbook Economics taught the PPC with “the famous pair, butter and guns”. America’s own war years show all three PPC cases in one run of data: a point inside the curve, a move along it, and a curve moving out.

Year	Jobless rate	Consumer spending	Defense output
1939	17.2%	970	26
1940	14.6%	1,020	45
1941	9.9%	1,092	232
1942	4.7%	1,066	826
1943	1.9%	1,096	1,357
1944	1.2%	1,127	1,550

• 1939 to 1941: inside the curve. With 17.2% of the labor force out of work in 1939, the economy was far inside its frontier. Defense output rose about ninefold by 1941, and consumer spending still rose 12.6%. More guns and more butter at once is exactly what a point inside the curve allows.
• 1942: along the curve. Unemployment fell to 4.7%, most of the slack was gone, and the trade-off appeared. Defense output rose 3.6 times in one year while consumer spending fell 2.4%.
• 1943 to 1944: the curve moving out. Both rose again while unemployment stayed under 2%. In the PPC model, more of both goods at full employment means the frontier itself moved outward.

Samuelson drew the same lesson in 1948: after 1940 the United States became “the arsenal of democracy” and enjoyed “civilian living standards higher than ever before, largely by taking up the slack of unemployment.” Economic historians still argue over how much civilian life really improved. The EH.Net encyclopedia notes that “according to some economists, the national living standard barely stayed level or even declined.” The consumer spending figures above are national totals, not a measure of how each household lived.

The four assumptions of a production possibilities curve

Every PPC is drawn under four assumptions. Break one and you get a different picture.

1st assumption – Constant technology

Technology is fixed for the period studied. Khan Academy defines the PPC for “current resources and technology”, and OpenStax defines efficiency “given the available inputs and technology.” Better technology is not a move on the curve; it shifts the curve.

2nd assumption – Fixed resources

The quantity and quality of the four economic resources are fixed: land (natural resources), labor, capital (tools, equipment and facilities) and entrepreneurship. More or better resources would shift the curve.

3rd assumption – Full employment of resources

Points on the curve assume every resource is fully and efficiently used. The AP framework describes the PPC as showing “the full employment level of output”, and NCERT says the frontier shows what can be produced “when the resources of the economy are fully utilised.” Idle resources put the economy inside the curve.

4th assumption – Only two goods

The model has two goods, or two broad groups of goods, so it fits on a flat graph: corn and cotton in NCERT, consumer goods and capital goods in many macroeconomics courses. Real economies make far more than two products; the two-good picture keeps the trade-off visible.

What shifts the production possibilities curve, and what does not

Only a change in what the economy can produce moves the curve. The AP framework: “The PPC can shift because of changes in factors of production as well as changes in productivity/technology.” The Federal Reserve’s teaching video names the same “two primary changes”: “a change in productive resources and technological change.” Everything else moves the economy to a different point, not the curve.

Change	What happens to the PPC
More labor, capital or land (a larger workforce, new factories)	Shifts outward
Better resources (education, training)	Shifts outward
Better technology for both goods	Shifts outward
Better technology for one good only	Pivots outward on that good’s axis
Resources destroyed or lost (war, disaster)	Shifts inward
Recession, unemployment, idle machines	No shift: the economy moves inside the curve
Price changes	No shift: the chosen point moves along the curve
Changes in what consumers want	No shift: the chosen point moves along the curve
Trade with other countries	No shift in production; consumption can go beyond the PPC

Growth versus recovery

Moving from inside the curve onto it is not growth. OpenStax separates the two cases. A society using its resources inefficiently can produce more “by improving efficiency and producing on the production possibilities frontier.” Growth is different: “as resources grow over a period of years (e.g., more labor and more capital)”, the frontier “will tend to shift outward.” Khan Academy states the exam point directly: “Going from an inefficient amount of production to an efficient amount of production is not economic growth.” BYU-Idaho’s course notes add: “the PPC does not shift when resources are left unused or when they are not used efficiently.”

Prices and preferences pick the point

Which point an economy chooses depends on what people want. OpenStax calls the chosen point allocative efficiency, “the combination that society most desires.” BYU-Idaho explains how a market finds it: “that combination is determined by supply and demand … the pricing mechanism signals to producers what consumers want.” A change in prices or tastes therefore moves the economy along its frontier, as the Wyndor example shows with numbers.

Capital goods today, a bigger frontier tomorrow

The point chosen today also changes where the frontier will be. NCERT lists the choice between “consumption goods” and “investment goods (like machine) which will boost production and consumption tomorrow.” Machines built today are more capital tomorrow, and more capital is one of the things OpenStax says shifts the frontier outward over time.

Limitations of the PPC model

• It is a snapshot. A Federal Reserve lesson plan calls it “a single snapshot in time”: resources, consumer preferences and production keep changing in a real economy.
• It rarely has real numbers. OpenStax draws its healthcare and education PPF without figures because “we do not know the exact amount of resources this imaginary economy has.” A factory is the exception: its capacities are known, so its frontier can be computed, as above.
• It does not say which point is best. Every point on the curve is efficient. Choosing among them needs information about what people want; CORE Econ adds indifference curves to the frontier for exactly this.
• It says nothing about who gets the output. “For whom” is a separate central problem in NCERT.
• It leaves out trade. With trade, a country can consume beyond its own PPC even though it cannot produce beyond it.
• It squeezes an economy into two goods. That keeps the picture clear but hides the many trade-offs inside each group.

PPC in AP Economics and CBSE Class XI

The same topic sits in different places depending on your course. These are the current official documents:

Course	Where the PPC is, and what you must do
AP Macro­economics (College Board, effective fall 2026)	Unit 1, Topic 1.2; Unit 1 is 5% to 10% of the multiple-choice section. Define the PPC; explain efficiency, opportunity cost, growth and contraction; calculate opportunity cost from a graph or table; draw a labeled graph
AP Micro­economics (effective fall 2026)	Unit 1, Topic 1.3, with the same PPC content as the Macro course
CBSE Economics, Class XI (2026-27)	Part B, Unit 4 “Introduction”, worth 4 of 40 marks: central problems of an economy; concepts of production possibility frontier and opportunity cost

Two details are easy to miss. First, CBSE teaches this in Class XI, although the prescribed NCERT book, Introductory Microeconomics, is still labelled “Textbook for Class XII”. Second, the NCERT chapter does not cover shifts of the frontier, while CBSE’s suggested Class XI projects include “Effect on PPC due to various government policies”. The shifts section above fills that gap.

In AP Macroeconomics the PPC comes back later: the course pairs it with the long-run aggregate supply curve, and the PPC is on the list of graphs students must be able to read and draw in both the multiple-choice and the free-response sections.

Who introduced the production possibility curve?

No single economist invented it. In “The Trade Theorist’s Sacred Diagram” (Federal Reserve Bank of Richmond, Economic Review, 1988), Thomas Humphrey traces the diagram through eight stages. Its earliest form is Irving Fisher’s: his 1907 book The Rate of Interest was “the first to combine indifference and transformation curves” in one diagram.

• Irving Fisher (1907) “invented the diagram to illustrate a problem in capital theory.”
• Gottfried Haberler (1930) “introduced the strictly concave production frontier version into foreign trade theory”, the bowed-out curve used today. In his 1936 book The Theory of International Trade he called it the “substitution-curve” and noted that under increasing costs it “is concave towards the origin.”
• Abba Lerner (1932) extended it to the world economy; Haberler records that Lerner called it a “production indifference curve.”
• Paul Samuelson (1948) headed the section in his textbook Economics “The production-possibility or transformation curve” and taught it with butter and guns, which he already called “the famous pair”.

FAQs

Using the PPC: the decision it leaves you

For a test, the PPC asks four things of you: label both axes, place each point on, inside or outside the curve, calculate opportunity cost as the amount given up divided by the amount gained, and say whether a change shifts the curve or only moves the point.

For a business, the same graph is a product-mix decision. Your capacity sets the frontier; prices tell you which point on it earns most. Price changes only move you along it. To move the frontier itself you add capacity or improve methods, and the bottleneck is where that buys the most.

How we researched this page

Rewritten 10 October 2026. We read the current College Board AP Macroeconomics and AP Microeconomics course frameworks (effective fall 2026), OpenStax Principles of Economics 3e, NCERT Introductory Microeconomics (reprint 2026-27) and the CBSE 2026-27 curriculum, CORE Econ, MIT OpenCourseWare, Federal Reserve teaching materials, Khan Academy and BYU-Idaho course notes, plus BEA and Census Bureau data for the war years and Thomas Humphrey’s history of the diagram. The corn and cotton figures are NCERT’s; the Wyndor Glass data are Hillier and Lieberman’s. Opportunity costs, the Wyndor frontier and its price and capacity cases are our own arithmetic, shown in the tables. All four diagrams were redrawn from those figures.

Correction. An earlier version of this page listed changes in prices and in consumer preferences as factors that shift the PPC, said the model does not account for opportunity cost, and used a product life cycle curve as its main image. All three were wrong and have been corrected.

References (read 10 October 2026)

• College Board, AP Macroeconomics Course and Exam Description, effective fall 2026 (Topic 1.2)
• College Board, AP Microeconomics Course and Exam Description, effective fall 2026 (Topic 1.3)
• OpenStax, Principles of Economics 3e, 2.2 The Production Possibilities Frontier and Social Choices
• NCERT, Introductory Microeconomics, Chapter 1 Introduction (reprint 2026-27)
• CBSE, Economics curriculum, Classes XI and XII, 2026-27
• Khan Academy, Lesson summary: opportunity cost and the PPC
• Khan Academy, Production possibilities curve (video, recession and growth)
• CORE Econ, The Economy 2.0: Microeconomics, glossary (feasible frontier, MRT)
• MIT OpenCourseWare, 14.54 International Trade, Lecture 6
• Federal Reserve Education, The production possibilities frontier: underemployment and economic growth
• Federal Reserve Education, The production possibilities frontier: increasing opportunity cost
• Federal Reserve Bank of St. Louis, lesson plan: Production Possibilities Frontier
• BYU-Idaho, ECON 150 Lesson 1
• Rittenberg and Tregarthen, Principles of Economics (LibreTexts), 2.2 The Production Possibilities Curve
• ISEG Lisbon, Operations Research exercise list (Wyndor Glass prototype from Hillier and Lieberman, section 3.1)
• KU Eichstaett-Ingolstadt, Wyndor Glass model and solution
• Constructor University, Operations Research Session 1 (Wyndor Glass data, profit per batch)
• BEA via FRED, Real Personal Consumption Expenditures (PCECCA)
• BEA via FRED, Real national defense, chain-type quantity index (B824RA3A086NBEA)
• BEA via FRED, National defense consumption expenditures and gross investment (A824RC1A027NBEA)
• BEA, NIPA Handbook, Chapter 4 (chained-dollar method)
• U.S. Census Bureau, Historical Statistics of the United States, Colonial Times to 1970, series D 85-86
• Christopher Tassava, The American Economy during World War II, EH.Net Encyclopedia
• Thomas M. Humphrey, The Trade Theorist’s Sacred Diagram: Its Origin and Early Development, FRB Richmond Economic Review, 1988
• Gottfried Haberler, The Theory of International Trade (1936), chapter XII
• Paul A. Samuelson, Economics: An Introductory Analysis (1948)

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