How do I know if I've defined my ICP too narrowly and I'm leaving obvious customers out?
The short answer
The warning sign isn't turning away customers, it's turning away people who buy fast, use it the same way, and refer others just like them. If you keep meeting a second group with near-identical pain and behaviour, your definition may be tighter than the reality. But resist widening just because someone waves money: one-off buyers who use the product differently will pull your roadmap apart. Look at your best customers' actual patterns, and widen only when a clearly adjacent group shows the same buying and usage behaviour. Treat this as an ongoing read, not a one-time decision.
Go deeper, your way
3 hand-picked resources, 3 link-checked. Pick how you want to dig in.
🎧 Podcast
✓ Link checkedFreeIntermediate
Why we picked it
Pete Kazanjy is blunt about defining a tight ICP from real signal (who actually buys and closes) rather than from who you wish would buy, which is the honest check on whether you have drawn the boundary in the wrong place. The ICP and personas segment (around the 36 minute mark) is the part to listen for. It is a practical, founder-doing-the-selling view of reading your own data to find where your best customers really sit.
On
Lenny's Podcastby Lenny Rachitsky (host), with Pete KazanjyAbout 90 minutes
Define your ICP tightly from where your product genuinely fits, then let outbound and closed-won data, not friendly intros, tell you who your best customers actually are.
Treat the ICP as a living definition you revisit as data comes in, so you can catch both an over-narrow cut and adjacent customers you had written off.
Founder-led selling is what surfaces this signal in the first place, because you hear the objections and the fits directly before handing sales to a team.
Why we picked it
This is the clearest piece we found on the actual question: when a tight ICP has become too tight and you are leaving real customers out. Jason Cohen (founder of WP Engine) gives you concrete conditions for when you have earned the right to broaden, plus a matrix for judging which adjacent customers are close enough to serve without breaking your product. It treats over-narrowing as a real risk, not just a virtue, which is the honest framing.
From
A Smart Bearby Jason CohenAbout a 15 minute read
You have likely earned the right to broaden once you have won roughly 5% or more of your defined segment, growth in your current channel is bottlenecked, or you have the profit to fund a second motion.
Score each candidate adjacent segment against six areas (marketing, sales, service, product, engineering, business model): if more than one needs a full overhaul, it is not really adjacent and you are probably chasing the wrong customers.
Expanding a narrow ICP is far easier than refocusing a broad one, so the fix for over-narrowing is a deliberate next segment, not blowing your definition wide open.
Why we picked it
Moore's classic maps the market you are timing your entry into: innovators and early adopters buy for very different reasons than the pragmatic early majority, and there is a real gap (the chasm) between them. If you enter while a market is still forming, this tells you who you are actually selling to and why proven demand feels so far off. Treat it as a starting point for reading market readiness, not a promise that patience alone wins.
