Link between individual supply and market supply

The Allocation of Resources – Supply

Individual Supply

Each producer (like a farmer, a factory or a freelancer) has an individual supply curve that shows the quantity they will sell at each price.

• Higher price → more incentive to produce → higher quantity supplied.
• Lower price → less incentive → lower quantity supplied.
• Costs (e.g., raw materials, labour) shift the curve.

Example: A baker sells cupcakes. If the price rises from £2 to £4, the baker might increase the number of cupcakes from 10 to 20 per day.

Market Supply

The market supply curve is the horizontal sum of all individual supply curves. Imagine all the bakers in town adding their cupcakes together at each price.

1. Take the quantity each producer supplies at a given price.
2. Add those quantities together.
3. Plot the total quantity against the price.

Mathematically:

$$S_M(P) = \sum_{i=1}^{n} S_i(P)$$

Where S_M is market supply, S_i is the supply of producer i, and n is the number of producers.

Linking Individual and Market Supply

Think of the market supply as a big group project. Each student (producer) brings their own work (individual supply). The final grade (market supply) is the sum of all contributions.

Key points:

• Market supply is always **upward‑sloping** because higher prices motivate more production.
• If a new producer enters the market, the market supply curve shifts right.
• If costs rise for all producers, each individual supply curve shifts left, pulling the market supply curve left too.