Price Elasticity of Demand Calculator

In 2026, a pricing analyst at a North American casual-dining chain runs a $25 → $30 menu test on the entrée-of-the-day. Quantity drops from 200 plates to 167. The PED of roughly −1.0 (unit elastic) tells her revenue is virtually unchanged — the price test failed to move the top line and might erode brand value. The widget plots her two points, draws the demand line, and color-codes the zone in under a second so she can move on to the next menu item.

Alfred Marshall introduced "elasticity of demand" in his 1890 Principles of Economics, the founding textbook of modern microeconomics. Marshall's diagrammatic approach — price on the vertical axis, quantity on the horizontal — is what every economics student still draws today. The widget's plot is a faithful replication of Marshall's original diagram, with two empirical points connected by a downward-sloping line and the elasticity number floating in the corner like a margin note.

Joan Robinson's 1933 The Economics of Imperfect Competition and Edward Chamberlin's 1933 Theory of Monopolistic Competition extended Marshall's framework to firms with pricing power. Robinson derived the optimal markup formula MR = P(1 − 1/|PED|) which appears in the formula card below. This is the basis of modern pricing-optimization software: airlines, hotels, e-commerce, and SaaS firms all run optimization loops grounded in Robinson's equation. The widget reports revenue change directly so you can see Robinson's logic operating in real time.

Henry Schultz's 1938 monograph The Theory and Measurement of Demand(University of Chicago Press) was the first large-scale empirical estimation of demand elasticities across hundreds of commodities. Schultz inspired the entire econometric demand-estimation tradition — including Houthakker's 1955 paper on luxury vs necessity elasticities, still widely cited. The peer-reviewed sources we anchor the preset values to all trace their methodology back to Schultz.

Irving Fisher, Markowitz, Modigliani-Miller, and Sharpe operated in a different but adjacent tradition — asset pricing rather than goods pricing. Fisher's 1907 Rate of Interest formalized time-value-of-money, which feeds into long-run vs short-run elasticity (consumers substitute more over time, raising long-run |PED|). Sharpe's 1964 CAPM provides the discount-rate framework that governs how companies value future demand streams when setting prices today.

By 2026 the US Department of Justice and the Federal Trade Commission both use PED in antitrust market-definition tests via the Horizontal Merger Guidelines' SSNIP (Small but Significant Non-transitory Increase in Price) test. The European Commission's 2024 Market Definition Notice references diversion ratios that are functions of cross-price elasticity. SEC public-company 10-K filings increasingly disclose pricing-power language in MD&A sections, and FASB ASC 606 (Revenue from Contracts) requires firms to disclose price-volume mix in revenue change explanations.

The eight category presets in this widget are anchored to peer-reviewed sources from 2010-2025 published in the American Economic Review, Journal of Health Economics, Energy Journal, and other leading outlets. The widget's color zones (green inelastic / amber unit / red elastic) replicate the visual convention used in Mankiw's Principles of Economics and the CFA Institute Level 1 Economics curriculum — making this tool useful for both classroom study and professional pricing-strategy decisions.