Supply and Demand Shifters: The Complete Cheat Sheet

Knowing what shifts the supply and demand curves is one of the most fundamental skills in AP Economics. Nearly every micro topic builds on it, and shift analysis appears on every single AP exam. If you can quickly identify which curve shifts and in which direction, you can answer dozens of multiple-choice questions and ace the foundational parts of FRQs.

This cheat sheet covers every major supply and demand shifter you need to know, organized for quick reference and easy memorization.

A Quick Review: Shifts vs Movements

Before diving into the shifters list, remember the critical distinction. A movement along a curve happens when the price of the good itself changes. This changes the quantity demanded or quantity supplied, but the curve stays in place.

A shift of the entire curve happens when something other than the good's own price changes. This changes demand or supply at every price level. The whole curve moves left or right.

If an exam question says "the price of coffee rises," that is a movement along the demand curve for coffee. If the question says "consumer income rises," that shifts the demand curve for coffee (assuming coffee is a normal good). This distinction is tested constantly. Review it interactively in the [supply and demand module](/micro/supply-and-demand).

Demand Shifters (What Shifts the Demand Curve)

Use the acronym TONIE to remember the demand shifters list:

### T - Tastes and Preferences

When consumers develop a stronger preference for a product, demand increases (shifts right). When a product falls out of fashion, demand decreases (shifts left).

Examples: A viral social media post makes a product trendy (demand shifts right). A health study links a food to illness (demand shifts left). A celebrity endorsement increases demand for a brand.

### O - Other Related Goods (Substitutes and Complements)

Substitutes are goods that serve a similar purpose. If the price of a substitute rises, demand for the original good increases. If Pepsi's price rises, demand for Coke shifts right because consumers switch.

Complements are goods used together. If the price of a complement rises, demand for the original good decreases. If the price of hot dog buns rises, demand for hot dogs shifts left because people buy the two together.

### N - Number of Buyers

More buyers in the market increase demand (shift right). Fewer buyers decrease demand (shift left).

Examples: Population growth increases demand for housing. Immigration increases demand for goods in the destination country. An aging population increases demand for healthcare services.

### I - Income

For normal goods, higher income increases demand (shift right). Most goods are normal goods. People buy more restaurant meals, vacations, and new clothing when they earn more.

For inferior goods, higher income decreases demand (shift left). Examples include instant noodles, used cars, and public bus rides. When income rises, consumers upgrade to better alternatives.

### E - Expectations

If consumers expect prices to rise in the future, current demand increases (shift right) as people buy now to avoid paying more later. If consumers expect prices to fall, current demand decreases (shift left) as people wait for the deal.

Examples: Announcement of a future tariff on imported cars increases current demand. Expected holiday sales decrease current demand as consumers wait for discounts.

Supply Shifters (What Shifts the Supply Curve)

Use the acronym ROTTEN to remember what shifts the supply curve:

### R - Resource Costs (Input Prices)

When the cost of inputs (labor, raw materials, energy) increases, supply decreases (shifts left). When input costs fall, supply increases (shifts right).

Examples: Rising oil prices increase transportation costs, shifting supply of shipped goods left. A decrease in the price of steel increases the supply of cars. Higher minimum wages increase labor costs, shifting supply left for labor-intensive businesses.

### O - Other Goods the Producer Could Make

If the price of an alternative good a producer could make rises, supply of the current good decreases as producers shift resources to the more profitable option.

Examples: If corn prices spike, a farmer might plant more corn and less wheat, decreasing the supply of wheat (wheat supply shifts left).

### T - Technology

Technological improvements reduce production costs and increase supply (shift right). Technology almost always shifts supply right; it rarely goes backward.

Examples: Better manufacturing robots increase supply of factory-produced goods. Improved agricultural techniques increase food supply. More efficient drilling technology increases oil supply.

### T - Taxes and Subsidies

Taxes on producers increase production costs and decrease supply (shift left). A per-unit tax shifts the supply curve up by the amount of the tax.

Subsidies reduce production costs and increase supply (shift right). A per-unit subsidy shifts the supply curve down by the amount of the subsidy.

This is important for AP exam questions about government intervention. A tax on cigarettes shifts the supply of cigarettes left, raising the price and reducing the quantity sold.

### E - Expectations of Producers

If producers expect the price of their good to rise in the future, they may reduce current supply (shift left) to sell more later at the higher price. If they expect prices to fall, they increase current supply (shift right) to sell before the drop.

### N - Number of Sellers

More firms entering the market increase supply (shift right). Firms exiting decrease supply (shift left).

Examples: Deregulation allows new firms to enter a market, increasing supply. A factory closure reduces the supply of the goods it produced.

How to Apply Shifters on the AP Exam

When an AP question describes a scenario and asks what happens to equilibrium price and quantity, follow this process:

Step 1: Identify what changed. Is it a demand shifter or a supply shifter? Use the TONIE and ROTTEN lists.

Step 2: Determine the direction. Does the shifter increase (shift right) or decrease (shift left) the curve?

Step 3: Trace the effect on equilibrium. An increase in demand (shift right) raises both price and quantity. A decrease in demand (shift left) lowers both. An increase in supply (shift right) lowers price and raises quantity. A decrease in supply (shift left) raises price and lowers quantity.

Step 4: If both curves shift simultaneously, you can determine one variable but not the other without knowing the magnitude. For example, if both demand and supply increase, quantity definitely rises but the effect on price is ambiguous.

Double Shifts: The Tricky Exam Questions

When both supply and demand shift at the same time, one variable is deterministic and the other is ambiguous:

Both increase: Quantity rises. Price direction is ambiguous.

Both decrease: Quantity falls. Price direction is ambiguous.

Demand increases, supply decreases: Price rises. Quantity direction is ambiguous.

Demand decreases, supply increases: Price falls. Quantity direction is ambiguous.

The AP exam loves these double-shift questions because they test whether you truly understand the underlying logic rather than just memorizing outcomes.

Common Mistakes with Shifters

Confusing a change in quantity demanded with a change in demand. A price change causes the former (movement along). An external factor causes the latter (shift).

Forgetting that income effects depend on the good type. Income increases shift demand right for normal goods but left for inferior goods. Always classify the good before determining the direction.

Ignoring supply shifters. Students tend to focus on demand and forget that changes in input prices, technology, and the number of sellers also move equilibrium. Many AP questions are supply-side questions.

Shifting the wrong curve. A change in consumer income shifts the demand curve, not the supply curve. A change in production technology shifts the supply curve, not the demand curve. Read the question carefully and identify whether the change affects buyers or sellers.

Memorization Tips

Write out the TONIE and ROTTEN acronyms from memory once per day during your study period. For each letter, give one example of a rightward shift and one example of a leftward shift. This active recall practice locks the shifters into long-term memory far more effectively than passive re-reading.

Practice identifying shifters in real-world news. When you see a headline about rising gas prices, ask yourself: which curve shifted, and why? This habit turns everyday information into AP exam preparation.

Build fluency with the interactive exercises in the [supply and demand module](/micro/supply-and-demand) on EconLearn, where you can apply different shifters and see how equilibrium price and quantity respond in real time.