Product Market Fit Is What Economists Call a Shortage

It was 2013, almost thirteen years ago now. I was on my MSc in Technology Entrepreneurship at UCL, reading Eric Ries and Ash Maurya, the two most prominent authors of the Lean Startup movement, until product-market fit and minimum viable product sounded like secret handshakes you earned in a build-measure-learn loop. ries-lean-startup maurya-running-lean I was learning a rigorous way to build under uncertainty. Real vocabulary, real discipline. What I had not yet learned was the older name economists had already given the same idea.

Fast forward to 2020. Covid had emptied London and colonised every classroom with Zoom. I was enrolled on the Chicago Booth Executive Program, sitting in my apartment in London for microeconomics while fifty-six cameras stared back from a grid dense enough to feel like a wall of witnesses. booth-exec Professor Lars Stole drew supply and demand, labelled the gap shortage, and kept lecturing as if the diagram were obvious. lars-stole I was not in Chicago. I was pinching the bridge of my nose at my laptop, trying to make sense of a concept that had sat in plain sight for seven years while I practised product design and strategy under a different vocabulary. Were product-market fit and that gap the same thing? They are, with a translation, not a synonym. Economists call excess demand at a price a shortage. Founders call the same squeeze product-market fit. Product-market fit is the fancy way of saying demand exceeds supply at a price and cost structure you can actually serve. Founders treat it like a secret level you only reach after enough A/B tests. An economist asks a blunter question: at the price you charge, do more people want what you sell than you can deliver without begging, discounting, or burning someone else's money? If yes, you have a shortage. If no, you have a surplus wearing a landing page. The jargon did not invent the condition. It renamed it and then sold you software to measure everything except the queue.

PMF Sells Workshops. Shortages Do Not.

The startup vocabulary around fit is vague on purpose. "Still searching for PMF" extends runway conversations. "We have PMF, now we scale" justifies headcount and ad spend. Accelerators, growth agencies, and analytics vendors all earn fees when fit stays a narrative milestone rather than a quantity on a diagram. A shortage is awkward in a board deck. It implies you are turning money away, saying no to bad-fit customers, or failing to hire support fast enough. Those are operational embarrassments with receipts. A funnel chart is an embarrassment you can workshop.

So the industry built a parallel religion: retention cohorts, Sean Ellis surveys, magic numbers, and the word feel in every Andreessen quote pulled out of context. ellis-pmf andreessen-pmf Those tools can inform. None of them is the thing itself. Maja Voje, in Go-To-Market Strategist, comes closer when she defines product-market fit as sufficient proof the market wants your product before you scale into a growth stage. voje-gtm That is a syllabus sentence for a shortage. Marshall had the diagram in 1890. marshall-principles Your stand-up had the acronym in 2013.

The MVP Was Meant to Prove Value, Not Ship Volume

Eric Ries was explicit about what minimum viable product was for. In "Minimum Viable Product: a guide," on Startup Lessons Learned on 3 August 2009, he defined it as "that version of a new product which allows a team to collect the maximum amount of validated learning about customers with the least effort." ries-mvp In The Lean Startup (Crown Business, 2011), he sharpened the rule: remove any feature, process, or effort that does not contribute directly to the learning you seek. ries-lean-startup The unit of progress was never the feature count. It was validated learning under uncertainty.

That is not how the syllabus landed in my cohort, and it is not how most founder decks read today. Somewhere between Ries and the sprint board, MVP became a product brief: ship the thinnest version, count sign-ups, call it learning. Economic value, the proof that someone will pay enough for you to serve them profitably, dropped out of the sentence. James C. Anderson and James A. Narus argued in the Harvard Business Review in November 1998 that suppliers who cannot quantify what their offering is worth in the customer's P&L will lose to whoever can. anderson-narus Ash Maurya tried to hold the other half in Running Lean (O'Reilly, 2012): problem-solution fit before product-market fit, with repeatable demand at a price that makes the model work, and three questions before you scale: will customers want it, will they pay, can you serve it profitably. maurya-running-lean We optimised what to build before we proved what it was worth. The industry mostly kept the MVP and skipped the price.

Marshall Drew It Before Your OKR Did

Alfred Marshall drew the diagram in Principles of Economics in 1890: a supply schedule, a demand schedule, and the point where they cross. marshall-principles Friedrich Hayek made the epistemic version in "The Use of Knowledge in Society," published in the American Economic Review in September 1945. hayek-1945 No central planner can survey every local trade-off. Prices and quantities aggregate knowledge nobody holds in one head. Thomas Sowell, in Basic Economics, states the mechanism plainly: a price set below the level that would prevail by supply and demand in a free market causes more to be demanded and less to be supplied, creating a shortage at the imposed price. sowell-basic-economics Hermann Simon, in Confessions of the Pricing Man, names the crossing point the market-clearing price, the only price at which supply and demand are in equilibrium. simon-pricing-man You do not need a perfect survey to know bread is scarce when the shelf is empty. You need a signal you cannot spin.

Marc Andreessen wrote the startup translation on his pmarca blog on 25 June 2007, in "The Pmarca Guide to Startups: Part 4: The only thing that matters." andreessen-pmf He did not say product-market fit was a vibe. He said you can always feel when it is happening. Customers are buying the product just as fast as you can make it. Usage is growing just as fast as you can add more servers. Money from customers is piling up in your company checking account. You are hiring sales and customer support staff as fast as you can. Reporters are calling because they have heard about your hot new thing. Read that list like an economist and it is a shortage symptom checklist. Demand is pulling product out of your hands faster than your supply curve can respond. Notice what his symptoms share: money at a price you can repeat, not a prototype someone praised in an interview.

Pull Is Readable. So Is Its Absence.

Avinash K. Dixit and Barry J. Nalebuff put the same idea in one line in Thinking Strategically: a stock price rises when the demand at the old price exceeds the supply. dixit-nalebuff Your startup version is a waitlist that grows when you do not discount, referrals that arrive before the ad budget, or a support queue that lengthens because usage is real. Customers return without a coupon code. The prospect accepts a later start date instead of walking. You feel the squeeze before the dashboard names it.

W. Chan Kim and Renée Mauborgne, in Blue Ocean Strategy, describe the opposite world: supply rising as global competition intensifies without a matching rise in demand, ending in commoditization, price wars, and shrinking margins. blue-ocean David Graeber, in Bullshit Jobs, goes further: when supply far outpaces demand in an industry, demand gets manufactured. graeber-bullshit-jobs Marketing can move a curve at the margin. It cannot invent a market that is not there at viable unit economics. I spent years after UCL watching my own company and others ship MVPs that proved interest and never proved willingness to pay, while the roadmap still listed three ideal customer profiles because the deck looked braver that way.

Not Every Queue Is Real

Say that plainly because hype wears the same costume. A waitlist can be manufactured. A price can be subsidised by venture capital until the shortage evaporates the day the subsidy does. Benjamin Graham, quoted by Warren Buffett in the 2008 Berkshire Hathaway shareholder letter, separates the two variables founders conflate: price is what you pay, value is what you get. buffett-2008 Flash sales create urgency without creating fit. Simon warns that pricing logic depends on existing prices and is often misunderstood, sometimes with disastrous consequences. simon-pricing-man If you are discounting to hit quota, if demos convert only when the quarter is ending, if paid media is doing the work referrals refuse to do, you are not in a shortage. You are pushing supply at people whose demand curve sits elsewhere.

That distinction saves you from two expensive errors. The first is polishing supply while demand is flat: prettier onboarding for a product nobody pulls. The second is mistaking supply constraint for demand failure: killing a product that people want because fulfilment is hard. An economist separates them by watching what happens when you raise price or tighten access. In a true shortage, some buyers stay and complain about wait time. In a fake one, the room empties. A smoke-test landing page that collects emails is not Maurya's repeatable demand at a workable price. maurya-running-lean It is a maybe.

I Sold Product Strategy. I Needed the Diagram.

Between 2013 and 2020 I did what the Lean Startup syllabus trained me to do at my own company. I was the founder practising product design and strategy the way the books taught: roadmaps, onboarding flows, launch narratives, another feature before anyone asked whether demand was real. I was not lying to investors or myself. I believed the vocabulary. I had Ries and Maurya under my arm and no Marshall on the whiteboard in my head. When we shipped an MVP and celebrated activation, I green-lit the next feature instead of asking Maurya's third question: can we provide this profitably at the price we had quoted in the room. maurya-running-lean

The company kept burning runway building product before we tested economic value. I delivered sharper flows and clearer strategy decks that made us look like we were moving. What I did not deliver, for years, was the sentence that finally landed on that Booth call: stop serving three demand curves when only one was pulling faster than we could hire. I gained a portfolio story about launch velocity. We lost quarters I counted as product progress instead of naming the shortage.

Your Arm Tightens Before the Number Appears

You have worn a blood pressure cuff in a clinic. The nurse pumps. Your bicep tightens before the machine beeps. Your body registers compression before your mind reads the number on the screen. Product-market fit works the same way if you let it. You feel it in the inbox that never empties, the customer success hire you needed last month, the referral you did not incentivise, the prospect who accepts a later start date instead of walking. The spreadsheet catches up later. The satisfaction score turns green after the pain is already old news.

If you are only looking at the monitor, you will misdiagnose. I did it for years after UCL, prioritising roadmaps and MVP backlogs because the syllabus never taught me to read the squeeze at a price that works.

The Strongest Case for Keeping PMF Mystical

Let me give the objection its fairest hearing, because technology is not a wheat field. Software scales at near-zero marginal cost. Network effects, switching costs, and data moats mean the supply curve bends in ways Marshall's chalkboard did not draw. Retention matters. Defensibility matters. A consumer social product and a vertical B2B tool share a word and not a geometry. In networked categories, fit may show up as density before it shows up as a queue. A marketplace needs buyers and sellers pulling at once; a one-sided waitlist can mislead. Reducing everything to "shortage" risks founder cosplay: pretending a waitlist equals a business when the unit economics are on life support, or ignoring product quality because a few loud users create artificial pull.

Fair enough. Economists would not rename your roadmap for you. They would ask whether quantity demanded exceeds quantity supplied at the price you set. Ries and Maurya never promised you could read that from week-one revenue alone. Ries wanted the fastest path to learning. ries-lean-startup Maurya wanted problem-solution fit before product-market fit, with demand proved at a price that makes the model work. maurya-running-lean The drift was ours: we turned learning into shipping and fit into a feature milestone. Andreessen himself described gradations: a product that can be used but is not great, versus a great product that cannot be kept on the shelves. The mistake is stopping at the adjective great and skipping the shelf. On 25 June 2007, in the same essay founders quote for inspiration, Andreessen listed operational symptoms, not poetry: customers buying as fast as you can make the product, usage outrunning server capacity, money piling up, support hiring lagging demand, reporters calling. andreessen-pmf That is quantity demanded exceeding quantity supplied at the terms you offered. Even at zero marginal cost, your time, your support hours, and your reputation are still finite supply. When fit is real, those bind first.

Product-market fit is what happens when the market wants more from you than you can comfortably deliver at a price that still makes sense. If nobody pulls without a discount and your calendar is not the bottleneck, you are not there yet, no matter what the dashboard calls it. Read your waitlist the way an economist reads a shortage diagram: same pressure, different accent. I kept three ideal customer profiles on our roadmap while referrals stacked up in one vertical; when paid media failed to manufacture the other two, my co-founder left before anyone named the shortage.