In AP Macro, input prices are the costs producers pay for factors of production (labor, raw materials, capital). When input prices rise, producing each unit gets more expensive and the supply curve shifts left; when input prices fall, supply shifts right (EK MKT-2.D.1).
Input prices are what it costs a firm to make its product. Think wages for workers, the price of steel or wheat, energy bills, the cost of machinery. They're the costs of the factors of production.
Here's why AP Macro cares. The supply curve is drawn assuming input prices stay constant. The moment they change, the whole curve moves. If oil gets more expensive, every gallon of gasoline costs more to produce, so refiners supply less at every price. That's a leftward shift of supply, not a movement along the curve. Cheaper inputs do the opposite and shift supply right. This is the difference the CED hammers in Topic 1.5: a change in the good's own price moves you along the supply curve (a change in quantity supplied), while a change in input prices shifts the entire curve (a change in supply).
Input prices live in Unit 1, Topic 1.5 (Supply) and directly support learning objective 1.5.C, explaining the determinants of supply. The essential knowledge statement EK MKT-2.D.1 names input prices explicitly as a factor that shifts the market supply curve. They're usually the first letter students learn in supply-shifter mnemonics (the "R" for resource costs in R-O-T-T-E-N).
But the real payoff comes later. In Unit 3, the exact same logic applies to short-run aggregate supply. A spike in input prices (an oil shock, rising nominal wages) shifts SRAS left and causes cost-push inflation. Every released FRQ that asks you to shift SRAS is secretly testing whether you understood input prices back in Topic 1.5.
Keep studying AP® Macroeconomics Unit 1
Supply Curve (Unit 1)
Input prices are the most common reason the supply curve shifts. Rising input prices shrink profit at every output level, so producers offer less at every price. The curve moves left. The curve itself, and the law of supply behind it, is covered in LOs 1.5.A and 1.5.B.
R-O-T-T-E-N (Unit 1)
This mnemonic lists the supply shifters, and resource (input) costs are the one tested most often. If you can sort "input price change = shift" from "own price change = movement along," you've already dodged the most popular wrong answer in supply MCQs.
Equilibrium Price (Unit 1)
An input price change doesn't stop at the supply curve. A leftward supply shift raises equilibrium price and lowers equilibrium quantity. AP questions love chaining it: input prices up, supply left, price up, quantity down.
Short-Run Aggregate Supply (Unit 3)
The macro version of the same idea. Economy-wide input price changes (especially wages and energy) shift SRAS. Rising input prices shift SRAS left and cause cost-push inflation, the setup behind many output-gap FRQs.
In multiple choice, input prices show up as the answer (or the trap) in supply-shifter questions. Classic stems ask which factor causes a leftward shift in supply, which scenario shifts supply right, or which option would NOT shift the curve. A per-unit tax on producers works the same way as an input price increase, raising the cost of each unit and shifting supply left. The trap answer is always a change in the good's own price, which moves you along the curve instead.
On FRQs, the term does its heavy lifting in Unit 3 graphs. Released questions like the 2023 and 2024 FRQ Q1 set up an economy in short-run equilibrium with an output gap and ask you to draw and shift AD-AS graphs. When a prompt mentions rising wages, oil prices, or resource costs, you shift SRAS left, label the new equilibrium, and explain the effect on price level and real GDP. Half the points come from correct labeling, so practice drawing the shift, not just naming it.
This is the single most-tested confusion in Topic 1.5. If the price of the good itself changes, you move ALONG the supply curve (a change in quantity supplied). If input prices change, the entire supply curve SHIFTS (a change in supply). Quick test: did the cost of making the good change, or just the price it sells for? Cost of making it changed = shift. Selling price changed = movement along.
Input prices are the costs of factors of production, like wages, raw materials, energy, and capital equipment.
Rising input prices shift the supply curve left; falling input prices shift it right (EK MKT-2.D.1).
A change in the good's own price causes a movement along the supply curve, never a shift. Only determinants like input prices shift the curve.
A per-unit tax on producers acts just like an input price increase, shifting supply left.
After a leftward supply shift from higher input prices, equilibrium price rises and equilibrium quantity falls.
The same logic scales up in Unit 3: economy-wide input price increases shift SRAS left and cause cost-push inflation.
Input prices are the costs producers pay for factors of production, like wages, raw materials, energy, and machinery. They're one of the determinants of supply in Topic 1.5, and changes in them shift the market supply curve (EK MKT-2.D.1).
They shift it. Higher input prices shift supply left, lower input prices shift it right. Only a change in the good's own price causes a movement along the curve, and mixing these up is the most common wrong answer on supply MCQs.
Input prices are what it costs to MAKE the good; the good's price is what it SELLS for. A change in input prices shifts the whole supply curve, while a change in the good's price just moves you to a different point on the existing curve.
On the graph, yes. A per-unit tax raises the cost of producing each unit, just like more expensive inputs, so both shift the supply curve left. AP questions use producer taxes as a stand-in for rising production costs.
Very much. In Unit 3, economy-wide input price changes (like wage increases or an oil shock) shift short-run aggregate supply. A leftward SRAS shift from rising input prices is the textbook cause of cost-push inflation, a setup that appears regularly in released FRQs.
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