Price Ceiling & Price Floor Diagram Maker
Rent controls, food price caps, minimum wages, agricultural price supports, price control diagrams turn up in every IB paper and countless IA commentaries. The key skill is placing the controlled price on the correct side of equilibrium and reading off the resulting shortage or surplus.
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IB EconGraph AI draws the control line, marks Qd and Qs at the controlled price, and labels the shortage or surplus gap for you, or gives you a clean canvas to construct it manually.
What the price ceiling and price floor diagram shows
Price control diagrams start from ordinary supply and demand, then add a horizontal price line:
- Price ceiling (maximum price): set below equilibrium, e.g. rent control. Quantity demanded exceeds quantity supplied, creating a shortage (excess demand).
- Price floor (minimum price): set above equilibrium, e.g. minimum wage, farm supports. Quantity supplied exceeds quantity demanded, creating a surplus (excess supply).
- Qd and Qs: read where the control line crosses each curve; the horizontal gap between them is the shortage/surplus, label it explicitly.
- Welfare effects: shade the deadweight loss and the transfers between consumers and producers for evaluation answers.
How to draw it in IB EconGraph AI
- Generate "price ceiling below equilibrium in the rental market showing the shortage" with AI, or add a horizontal line to the supply-and-demand template.
- Place the ceiling below (floor above) the equilibrium, the most common student error is putting it on the wrong side, where it has no effect.
- Drop annotated points where the price line crosses D and S; label Qd and Qs on the axis.
- Draw a labelled bracket or arrow for the shortage/surplus gap using the line and text tools.
- Shade the DWL triangle if the question asks about welfare or efficiency.
IA & exam tips
- A non-binding control (ceiling above equilibrium) is a legitimate evaluation point, you can draw both cases side by side in one project.
- For minimum wage articles, relabel the axes (Wage rate / Quantity of labour), double-click any label to edit it.
- Discussing black markets? Mark the price consumers would pay for the restricted quantity Qs up on the demand curve.
Frequently asked questions
Which side of equilibrium does a price ceiling go?
A binding price ceiling sits below equilibrium (it caps the price), creating a shortage. A binding floor sits above, creating a surplus. The AI places them correctly from your description.
Can I show both a ceiling and a floor?
Yes, projects let you keep multiple related graphs together, or you can place both lines on one canvas for a comparison diagram.
Can I label the shortage gap?
Yes, use the text label tool for "shortage = Qd − Qs" and the line tool for the bracket arrows.
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