Individual demand: The blueprint of your shopping choices
1. The anatomy of a single choice: Wants vs. budget
Imagine you are in a shop with $10 in your pocket. You see a chocolate bar for $2 and a comic book for $8. You want both, but you also want to keep some change. Individual demand is not just about dreaming; it requires ability to pay. Economists say that demand exists only when desire meets purchasing power. If the chocolate bar costs $10, you might still want it, but you cannot afford it — so your individual demand at that price is zero.
For a younger student: think of your weekly allowance. When the price of ice cream is low, you buy two scoops. When the price doubles, you might buy only one, or switch to a cheaper popsicle. That is your personal demand schedule — a table of how many units you buy at each price.
2. From numbers to a curve: The demand schedule & graph
Economists love tables. A demand schedule lists possible prices and the corresponding quantity a single consumer will buy. Let’s build one for Mia, a high school student who buys energy drinks.
| Price per can ($) | Quantity demanded (cans/week) | Why Mia buys this amount |
|---|---|---|
| 1.00 | 7 | Super cheap — she stocks up |
| 1.50 | 5 | Regular price — buys for school days |
| 2.00 | 3 | A bit expensive — only Friday treat |
| 2.50 | 1 | Almost never — only if very tired |
| 3.00 | 0 | Too expensive — buys iced tea instead |
If we plot these points on a graph (price on the vertical side, quantity on the bottom side), we get a downward-sloping line. This is Mia’s individual demand curve. Every point tells a story about her willingness at that exact price.
3. Two invisible forces: Income effect & substitution effect
Why do we buy less when prices rise? Two reasons. Income effect: if a pizza slice goes from $2 to $4, your $10 feels like only $8 — you are effectively poorer. Substitution effect: higher price makes other goods look better. Instead of pizza, you buy a burrito. Both effects work together to shape your individual demand.
🎮 Real-world lab: How Leoʼs demand changed twice
Leo is 14 and loves video games. Last month, his favorite game cost $60. He saved his birthday money and bought one copy — that’s his individual demand point. This month, the price dropped to $30 in a flash sale. Leo bought a second copy as a gift for his friend. His quantity demanded increased from 1 to 2. But something else happened: Leo got a part-time job. His income rose, so even at $60, he might now buy two games. This is a shift in demand — the whole curve moves right. Individual demand is not fixed; it changes with income, tastes, and prices of other goods.
Complementary goods example: Leo also buys an online subscription ($10/month) to play with friends. If the subscription price rises to $20, he might cancel it — and then he will also buy fewer new games because he plays less. His demand for games falls even if the game price stays the same. That’s how complements work.
❓ Important questions about individual demand
No. In economics, wanting is not enough. You must have the ability to pay. A child wanting a sports car without money creates zero demand. But if that child saves allowance for years and can buy a toy model car at $15, that is real individual demand for the toy.
Yes! If you are allergic to peanuts, your demand for peanut butter is zero at any price. If you don’t like a music style, your demand for concert tickets is zero even if they are free. Tastes and preferences are powerful determinants.
Absolutely not. Each person has a unique demand curve. A basketball player drinks 3 liters of water after training; an office worker drinks 1 liter. Some people love coffee, others hate it. Market demand is just the sum of all individual demands.
🔍 Conclusion: The tiny atom of the market
📚 Footnote: Terms & abbreviations
[1] Demand schedule: A table that shows the relationship between the price of a good and the quantity a single consumer is willing to buy, holding other factors constant.
[2] Income effect: The change in quantity demanded because a price change makes the consumer feel richer or poorer.
[3] Substitution effect: The change in quantity demanded because the good becomes more expensive or cheaper relative to other goods.
[4] Complement: A good that is used together with another good (e.g., gaming console and games).
[5] Price elasticity of demand: A numerical measure of how responsive quantity demanded is to a price change; often called E_d.