Product-Market Fit Has A Boring Definition And Most Founders Ignore It

Product-market fit is one of those concepts that sounds obvious right up until somebody asks you to define it.

The lazy answer you’ll hear everywhere is that PM fit is like a certain kind of content: you know it when you see it. Thanks. Very actionable.

We’ve spent years studying this, across a startup that never reached it, several hundred investments, and tens of thousands of companies reviewed. Here’s a definition you can actually use.

What does product-market fit actually mean?

You have product-market fit when you can repeatably acquire customers for less than what those customers are worth to you.

That’s it. It’s a plain business statement. Are your costs lower than your revenues? Are you profitable on the customers you bring in?

Not earth-shattering. Also not what most founders are measuring when they claim they have it.

Why is this so hard to assess early on?

Two reasons, and they’re both moving targets.

First, the time scale is unclear. At t equals infinity this has to be true or you don’t have a sustainable business. Anywhere between now and then, you can run unprofitably.

Second, when you’re starting out you don’t know what a customer is worth to you yet, and you don’t know what your costs will look like at scale. Two unknowns on both sides of the equation make profitability very hard to calculate.

So with a V1 product, ask a simpler version of the question: is there a channel that can get me customers profitably at some level of scale? A channel, as opposed to a pile of one-off deals that came from eight different places and can’t be repeated.

That word “repeatable” is doing all the work here. It’s very possible to brute force your way to a $1M run rate with no repeatable sales process. Investors know this and they won’t back it.

Why should you think about PM fit in stages?

Because it isn’t a single door you walk through once.

A better framing is to ask which benchmark you have PM fit for. Do you have PM fit for Series A levels, meaning can you get to roughly $1M to $3M run rate through repeatable acquisition channels?

Then the next question. Can those same channels carry you to Series B benchmarks, around $10M run rate? Series C, around $100M?

What got you to the first milestone frequently stops working at the next one. Each stage is its own version of the problem.

Can you lose product-market fit?

Yes, and it happens all the time.

Since PM fit is about repeatable customer acquisition, anything that breaks the repeatability takes your PM fit with it. You saturate a channel. A competitor saturates it for you. Demand for what you sell shifts. Channel costs rise until the math stops working.

Heroku is a clean example of losing it and getting it back. They started with a platform for Ruby developers and customer acquisition was easy. Then they saturated that market. To grow to the next level they had to expand the product to support other programming languages, which unlocked a new set of customers and got them back to PM fit.

Having PM fit at one stage and losing it at the next is normal. Panicking about it is optional.

Does raising a lot of money mean you have it?

No. Raising money and having PM fit are separate achievements that often get confused.

There are companies that make it all the way to IPO without profitable, repeatable customer acquisition. You can raise on a big vision plus some early proof points for a very long time. True PM fit is profitable customer acquisition that supports a sustainable company on its own.

If you’re benchmarking yourself against a competitor’s funding announcement, you’re measuring the wrong thing. That round tells you they sold a story well. It says nothing about whether their unit economics work.

What do you do if acquisition isn’t profitable yet?

When costs are already reasonably optimized, it’s usually easier to raise what a customer is worth than to cut what they cost. So the common move is to upsell or expand the offering.

Marketplaces do this by selling you one thing and then many things. GoDaddy sells hosting, then domains, then email, then security. Expedia sells flights, then rental cars, then hotels, then tours.

SaaS companies upsell as the customer grows. Slack starts free, then you pay for chat history, then you buy more seats as your team expands.

For fundraising purposes it’s fine to be unprofitable at the start if you can show a clear path to increasing lifetime value and making the sales process repeatable. Sell that path convincingly and you can afford to acquire customers unprofitably for a while.

Who gets to sell that story, though?

Here’s the part that often goes unsaid. Selling the “path to PM fit” story is much easier for some founders than others.

Pedigree and network make it easy. If you have those, the dream sells itself. When a famous VC says everyone should just have a big vision and raise big money, that advice is coming from inside a bubble.

If you’re a first-time founder with no connections, in the “wrong” geography, with an unusual background, or from a demographic investors haven’t pattern-matched in favor of, following that advice will hurt you.

Get an honest read on how much money you can realistically raise before you architect a plan that requires more. Your runway dictates how much you can build and how much you can tackle at each step.

Say you were building Expedia with limited capital. You might build only flight search. You might find few channels that profitably deliver customers, and you might saturate at a lower run rate.

You can still use that progress to raise more. It proves you can execute. Then you sell the rest of the vision: what you’ll build next, which customers that unlocks, and how it raises lifetime value so you can pour more into acquisition.

The end goal stays the same. Repeatable, profitable customer acquisition channels that can scale to the $100M per year level, reached as cash efficiently as you can manage.

Everything else is a story about getting there.

Until next time,

Dunky, the “still testing channels” hippocorn