There's a mix-up that comes up constantly when a small business starts running its own online ad campaigns, and it costs real money: treating someone who "has an interest" in a topic the same as someone who "has intent" to buy something related to that topic. They sound similar, and they sometimes overlap in the same person, but they're completely different mental states, and ad platforms (Google, Meta, LinkedIn) treat them as separate targeting categories for a very concrete reason: they convert in radically different ways.
An interest audience is people who, based on past behaviour, like things related to your sector: they follow fitness accounts, have liked home decor pages, consume personal finance content. An intent audience is people who, right now or very recently, have shown an active signal that they're trying to solve something specific: they've searched "best gym near me" on Google, visited price comparison pages, added a product to their cart and not checked out. The difference isn't subtle: one is a general affinity, the other is an active need.
How these audiences are actually built
In Google Ads, the strongest intent audiences are "in-market" segments, which Google builds by analysing recent searches, sites visited, and browsing behaviour that signal someone is comparing or about to buy in a specific category: "in-market for bathroom renovations," "in-market for car insurance." These audiences combine naturally with search campaigns, where the actual keyword the user types is already the strongest intent signal that exists.
On Meta (Facebook and Instagram), interest audiences are built from pages a user follows, topics they interact with, and broad categories Meta itself defines ("interested in yoga," "interested in entrepreneurship"). They're useful for reaching a lot of people with a generic affinity, but they say nothing about what stage of buying that person is at. The most reliable intent audience within Meta doesn't come from "interests" at all, it comes from your own pixel: people who visited your site, viewed a specific product page, started a checkout without finishing it. That's a real intent signal, generated by their own behaviour rather than external categorisation.
Which funnel stage to use each one for
This is where the most money gets lost from misuse. Interest audiences work well at the top of the funnel: when the goal is introducing a brand or product to people who don't know you yet but who fit your profile. Cost per click or impression there tends to be cheaper, but immediate conversion is low, because most of those people aren't looking to buy at that specific moment; they simply match the profile.
Intent audiences work better in the middle and bottom of the funnel: when the goal isn't "raise awareness" anymore but "capture a decision the person is already making." Cost per click here tends to run higher (there's more competition for that same person, because other advertisers have picked up the same signal), but the conversion rate is noticeably higher, because you're not creating a need, you're answering one that already exists.
The classic mistake is putting the whole budget into interest audiences expecting immediate sales ("well, they like the topic, they must buy"), and getting frustrated at a sky-high cost per sale. The opposite mistake, less common but also costly, is sticking only to intent audiences and ending up with reach so small the campaign never grows, because the number of people showing active intent at any given moment is, by definition, much smaller than the number of people with a general interest.
A concrete example to make it clear
Picture a dental clinic. An interest audience would be "people interested in aesthetics and personal care, aged 30-55, in your city": a broad group, relatively cheap to reach, but the vast majority of whom aren't thinking about visiting the dentist at this specific moment. An intent audience would be "people who searched 'dental implant price' or 'teeth whitening near me' on Google in the last 7 days," or "people who visited your pricing page but didn't book an appointment." The first group needs an ad that builds interest and trust (who you are and why to trust you, before anything else); the second group needs an ad that removes the last hesitation to act now (clear pricing, appointment availability, a guarantee).
How to combine them without wasting budget
The strategy that works best for a small business on a limited budget isn't choosing one or the other, it's staging them according to where the campaign is. Start with intent audiences (the priciest per click but the fastest to convert) to validate that your product, price, and landing page actually work; that's where you get your first sales and learn which message lands. Only once that's proven, expand into interest audiences to grow volume, knowing cost per sale will rise but that you'll be feeding the funnel with new people who, later on, will also enter remarketing and intent signals once they're closer to deciding.
The mistake of confusing demographic targeting with intent targeting
There's a third type of targeting that often gets mixed up with the previous two by mistake: purely demographic targeting (age, gender, location, estimated income level). Demographics are neither interest nor intent, they're simply a way of narrowing down the universe of people your ad gets shown to, and on their own they say nothing about whether that person is thinking of buying. The common mistake is launching a campaign targeted only at "women aged 30-45 in Madrid" and expecting intent-campaign results, when in reality you're running a pure demographic-reach campaign with no real behavioural signal behind it at all. Demographics work well as an additional filter layered on top of an already defined interest or intent audience (for example, "in-market for car insurance" plus "located in Madrid"), but they shouldn't be the only targeting criterion for a campaign chasing short-term sales.
Another nuance worth keeping in mind is that intent has an expiry date. Someone who searched "best gym near me" three months ago has probably already made a decision, and continuing to show them the same intent-based ad makes no sense; most platforms let you limit these audiences' time window (7, 14, 30 days) precisely to avoid spending budget on people whose intent has already resolved, one way or the other.
Frequently asked questions
Which audience should I use if my budget is very small?
Always start with intent, even if the cost per click is higher. With a limited budget, it's better to spend on fewer clicks from people already deciding than a lot of cheap clicks from people who aren't thinking about buying yet.
Are interest audiences good for anything, then?
Yes, they're very good for growth and mid-term brand building, but you need to measure them with different metrics than intent audiences: reach, frequency, cost per thousand impressions, not immediate cost per sale. Judging an interest audience by an intent audience's yardstick leads to cancelling campaigns that were actually doing their job well.
Can I combine both audiences in the same campaign?
It's better not to mix them within the same ad or ad set, because it dilutes the algorithm's learning and the message that works for one usually doesn't work the same way for the other. It's preferable to run separate campaigns or ad sets, each with messaging adapted to the mental stage that audience is in.