Supply and Demand Curve Calculator

Calculator

Example Data Table

Formula Used

The calculator uses a linear demand curve and a linear supply curve.

Demand: Qd = a - bP

Supply: Qs = c + dPs

Tax or subsidy wedge: Ps = P - tax + subsidy

Equilibrium: a - bP = c + d(P - tax + subsidy)

Buyer price: P = (a - c + d(tax - subsidy)) / (b + d)

Quantity: Q = a - bP

Demand elasticity: Ed = -b × P / Q

Supply elasticity: Es = d × Ps / Q

How to Use This Calculator

1. Enter the demand intercept and demand slope.
2. Enter the supply intercept and supply slope.
3. Add tax or subsidy values if needed.
4. Choose a price floor or ceiling when testing controls.
5. Enter a price to test for surplus or shortage.
6. Press Calculate to view results above the form.
7. Use CSV or PDF buttons to save the report.

Supply and Demand Curve Calculator Guide

A supply and demand curve calculator helps turn simple market assumptions into useful price signals. It models how buyers react when price rises. It also models how sellers react when price changes. The tool uses linear equations, so every input has a clear meaning. You can test a normal market, a taxed market, a subsidized market, or a controlled market.

Why equilibrium matters

Equilibrium is the point where quantity demanded equals quantity supplied. At that point, planned purchases match planned sales. No shortage exists. No unsold surplus remains. Managers use this point to study pricing, output, and policy effects. Students use it to understand graph intersections and market balance.

What the inputs represent

The demand intercept shows the quantity people would buy at a zero price. The demand slope shows how fast demand falls as price increases. The supply intercept shows the starting quantity sellers offer. The supply slope shows how fast supply rises as seller price improves. Tax and subsidy inputs shift the seller side of the market. They also create a wedge between buyer price and seller price.

How results are interpreted

The calculator reports buyer price, seller price, equilibrium quantity, market gap, surplus, shortage, and elasticities. Consumer surplus estimates buyer benefit above the paid price. Producer surplus estimates seller benefit above the supply reservation price. Government net revenue shows the value collected from taxes minus subsidy cost. These values make scenario comparison easier.

Practical uses

Use the tool before changing a product price. Compare the current price with the estimated equilibrium price. Check whether a floor causes surplus. Check whether a ceiling causes shortage. Review elasticity before discounts or price increases. A high absolute demand elasticity means buyers react strongly. A low value means demand is less sensitive. The downloadable reports help preserve assumptions, curve points, and final results for later review.

Reading the curve table

The curve table lists several prices, expected demand, expected supply, and the gap. A positive gap means surplus. A negative gap means shortage. The graph uses the same points. This makes the model transparent. You can adjust point count for smoother curves or smaller reports. Use careful inputs because weak assumptions produce weak market forecasts.

FAQs