Shift supply and demand curves and see equilibrium price and quantity adjust. Explore elasticity, surplus, and price controls.
Set up a market as two lines - demand sloping down, supply sloping up - and this tool draws both, finds where they cross, and reports the equilibrium price and quantity that clear the market. Drag a curve, change a slope, or impose a price control, and it recomputes the crossing along with elasticity at the equilibrium and the consumer and producer surplus triangles. The thing most people get wrong: a ceiling set below equilibrium does not make the good cheaper for everyone. It chokes off supply, and the quantity actually traded falls - which is exactly what the policy debate is about.
A concrete input and expected output from the current implementation.
Input
Demand: Qd = 100 - 2P. Supply: Qs = 10 + 3P. Then add a price ceiling at 12.
Expected output
Equilibrium price 18, quantity 64. With the ceiling at 12: quantity demanded 76, quantity supplied 46, so 46 units trade and the shortage is 30. Elasticity of demand 0.56 (inelastic), of supply 0.84.
Setting Qd = Qs gives 100 - 2P = 10 + 3P, so P* = 18; substituting back, Q* = 64 in both curves. At a ceiling of 12, supply is the binding side: 46 offered against 76 wanted, hence a 30-unit shortage.
Each curve is a function of price: demand falls as price rises, supply rises as price rises, and the equilibrium is the price where the two quantities are equal - the crossing point on the chart. With linear curves, the tool solves two equations in two unknowns, plots the intersection, marks price and quantity on the axes, and reports the surplus triangles and elasticity at that point.
A ceiling or floor binds only on the wrong side of the equilibrium price: a ceiling below it, a floor above it. When a control binds, the quantity traded is the smaller of what buyers want and what sellers offer at the controlled price - a shortage under a ceiling, a surplus under a floor. The tool shades the gap and recomputes the surplus, exposing the deadweight loss.
Only if supply can respond. At a ceiling of 12 in the example market, buyers want 76 units but sellers offer only 46, so 46 change hands - supply, not demand, is the binding side, and the 30-unit gap is the shortage. The good is cheaper only for the buyers who still get it, and total surplus falls by the deadweight loss.
Demand's elasticity is quoted as an absolute value, so the tool shows a positive number even though the underlying slope is negative - that is why price and quantity move in opposite directions. The number is the size of the response, and 1 is the boundary: below 1 inelastic, above 1 elastic. Total revenue peaks where elasticity equals 1 on a linear demand curve.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
Calculate percentages, percentage change, and what percent one number is of another with step-by-step breakdowns.
Calculate tips and split bills between multiple people with customizable tip percentages and rounding options.
Calculate monthly payments, total interest, and generate amortization schedules for loans and mortgages.
Calculate Body Mass Index from height and weight with category classification and healthy range guidance.
Calculate sale prices, savings amounts, and final costs after single or stacked percentage discounts.
Compute mean, median, mode, standard deviation, variance, and other descriptive statistics from a data set.