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Case study · Influencer marketing

How we cut influencer CPA by 55% for Gymshark

20 April 2026~6 min readIMPULSE
Working with ambassadors: selection by data rather than by follower count.
Working with ambassadors: selection by data rather than by follower count.

The brand is built on influencers. There are hundreds of them, across several Eastern European countries, and at some point the team simply stopped keeping up. Every ambassador has to be found, assessed, agreed and tracked. With twenty people it worked. At two hundred, CPA started climbing and lead quality started falling. The classic ceiling of a manual process.

They came to us with a framing we hear often: "the channel seems to work, but scaling it is frightening." Here is what we did and why it worked — without embellishment, because some of the decisions looked questionable until the numbers came in.

Why reach and likes lie

The standard logic for picking an influencer: look at reach, look at engagement, look at attractive statistics. The problem is that all of those metrics describe popularity, not a willingness to buy. A creator with a million followers and plenty of likes may sell nothing, while a niche author with an audience of thirty thousand delivers a steady stream of orders.

We started from a simple premise: reach does not buy anything, audience-to-product fit does. Which means an influencer should be assessed not by how many people see them, but by how closely those people resemble the ones already buying from the brand.

−55%cost per acquisition through influencers after moving to scoring and server-side attribution
20%of ambassadors produced most of the result — the rest consumed budget
hundredsof influencers across several countries, managed by hand

A model instead of a manager's intuition

We built a model that predicts not reach but the expected conversion rate of a specific collaboration. Inputs: the influencer's audience patterns and the profile of the brand's actual buyers. Output: an estimate of how many orders this creator is likely to bring, and at what cost.

The key word is patterns, not likes. The model looked at audience structure, subject matter and behaviour rather than vanity metrics. The manager still made the decision, but now with a forecast in front of them rather than a feeling that "this one looks alright".

−55%
Reduction in CPA on influencer campaigns. Branded traffic share rose 20%, and the channel's ROI became the highest of all paid channels in the region.
With twenty people, a spreadsheet copes. With three hundred, the spreadsheet stops being a tool and becomes a source of errors.

Attribution you can trust

A good model is useless if you do not know what actually happened after a post went up. With influencers this is a sore point: someone sees a story and buys three days later from a phone — try connecting the two.

We tied every collaboration to a unique promo code linked to server-side events. Not simply "10% off with code BLOGGER", but a code that connects at server level to a specific session and order. That gave honest attribution down to the session — showing not just how much an influencer sold, but the real cost of acquisition rather than the one last-click paints.

The model answers "who to work with". Attribution answers "did it work". Without the second, the first is guesswork.

Automated budget allocation

The last piece was the one the team initially received with suspicion. We arranged for successful collaborations to scale without manual sign-off. As soon as a pairing hit its targets, its budget increased automatically, under rules agreed in advance.

The fear is understandable: "what if the system scales something it shouldn't". So the rules were strict, with ceilings and stop conditions. In exchange, the main bottleneck disappeared — a person who could not physically review hundreds of collaborations every week. The system handled the routine; managers made the strategic calls.

Where this will not work

The approach needs volume: the model requires data from at least several dozen placements, otherwise the scoring is guesswork. If you have five influencers, count by hand — it is cheaper and more honest.

The second condition is server-side attribution. Without it the model learns from data in which some conversions are missing, and confidently reproduces that error.

What transfers to other brands

Three things, in descending order of how universal they are.

  1. Honest attribution first. Before optimising anything, know what actually happened. This applies at any scale and is usually the cheapest fix available
  2. Assess by audience fit, not by reach. Even without a model, comparing a creator's audience against your buyer profile beats sorting by follower count
  3. Automate the routine only after the process is measured. Automating an unmeasured process scales the error rather than the result

We build this kind of automation where the volume justifies it, and fix attribution where it does not yet exist.

FAQ

Why don't reach and engagement predict sales?

Because they describe popularity, not purchase intent. A creator with a million followers may sell nothing, while a niche author with thirty thousand delivers a steady stream of orders. What matters is how closely the audience resembles people who already buy from the brand.

What did the model actually predict?

The expected conversion rate of a specific collaboration, not reach. Inputs were the creator's audience patterns and the profile of the brand's real buyers. Output was an estimate of how many orders that creator would likely bring and at what cost.

Why is server-side attribution necessary here?

Because someone sees a story and buys three days later on a different device. Without server-side events tied to a unique promo code, you cannot connect the two, and you end up judging creators by last-click.

What is the automated budget allocator?

A rule-based system that scales spend on collaborations already hitting their targets, without waiting for manual sign-off. Rules include caps and stop conditions.

Wasn't there a risk the system would scale the wrong thing?

Yes, which is why the rules were strict, with ceilings and stop conditions. The trade-off was removing the real bottleneck: a person who could not physically review hundreds of collaborations every week.

How many influencers do you need for this to work?

Enough for the model to learn from — at least several dozen placements. With five influencers, count manually. It is cheaper and more honest.

What did the results look like?

Cost per acquisition through influencers fell 55%. Branded traffic share rose 20%, and the channel's ROI became the highest of all paid channels in the region.

Can this be transferred to a smaller brand?

The attribution part, yes, and it is usually the first thing worth fixing. The scoring model needs volume. Without it, you are automating a guess.

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Sources. All figures come from our own work on this engagement and are specific to it. They describe what happened on this account and are not an industry benchmark or a promise of similar results.