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Don’t bid your way out of rising cost per acquisition. Build your way out.
U.S. retail media ad spend is on track to hit $69.33 billion in 2026, according to eMarketer. Yet across the industry, brands scaling that investment are watching their cost per acquisition (CPA) climb at the same time, with more spend and worse efficiency. The instinct is to go straight into the ad account and start pulling levers: tweak bids, reshuffle audiences, reallocate spend. Most of the time, that’s the wrong place to look.
In isolation, those actions make sense. But they rely on the assumption that the source of inefficiency sits within the ad account itself.
In reality, many of the largest drivers of CPA sit upstream or downstream of media: the strength of the offer, the quality of the creative, and the effectiveness of the conversion journey.
This means if the goal is to reduce CPA, the question isn’t just what to optimize in-platform. As this article from Brainlabs explains, it’s also critical to understand where the inefficiency is actually coming from.
You’re probably looking in the wrong place
A CPA problem is often a conversion problem in disguise. The ad is doing its job, getting people to the site. What’s failing is everything that happens after the click: a product page that doesn’t convert, an offer that isn’t competitive, a checkout with too much friction. Optimizing media spend against a broken funnel just means spending more efficiently on something that isn’t working.
The first things to audit are your product feed and your offer. The feed containing your product titles, descriptions, prices, and images is what platforms use to serve shopping and retail ads, so if that data is incomplete or poorly structured, performance will suffer regardless of how well you bid. If the offer itself isn’t compelling on price or value, better targeting won’t compensate for it.
Bid strategy sits at the end of that list. It’s a useful tool for extracting efficiency from a program that’s already working, but it can’t create efficiency where the fundamentals aren’t there. The same logic applies to channel diversification: Expanding into new platforms because they’re growing or because a rep made a compelling case isn’t a demand strategy. Channel decisions should follow where your audience is and what role that channel plays in the wider system, not trend cycles.
The levers that actually move it
Once the conversion fundamentals are sound, two things tend to move CPA: creative and audience structure, and both are consistently underinvested.
On creative, the numbers are striking. A 2022 Nielsen study commissioned by Meta examined three years of marketing mix modeling data across 41 brands and found that campaigns with high-quality creative achieved 35% greater effectiveness. Separately, Google’s own research attributes 70% of campaign success to creative. Those aren’t marginal gains from asset refresh cycles. They reflect the difference between treating creative as a set-and-forget task and running it as a proper testing system.
The most effective approach treats creative as a rolling test system instead of a series of one-off campaigns. Running multiple variants per ad set simultaneously, each isolating a single variable such as the opening hook, format, or offer, generates clearer signals about what’s actually driving performance. Rather than cutting to a fixed timeline, each variant runs until it reaches a minimum spend threshold before decisions are made. Top performers get scaled, mid-performers get iterated, and bottom performers are cut quickly. The goal is to build a portfolio of working assets and feed learnings continuously into the next round, so performance compounds rather than resets each cycle.
Audience structure follows the same logic. Running the same ad to everyone, cold prospects and people who have visited the product page five times alike, treats the funnel as flat when it isn’t. The message, offer, and format that works for someone who has never heard of a brand is different from what works for someone already warm, and the inefficiency compounds at scale.
The fix is to structure audiences in clear layers: At a minimum, cold prospecting, engaged users, and high-intent or existing customers, each with distinct messaging and creative aligned to where they are in the journey. What moves someone between layers should be behavior rather than time. A site visit or video completion shifts someone from cold to warm. Repeated interactions or an add-to-cart moves them into high-intent. That way, discovery-led creative reaches people at the top, proof and product detail does the work in the middle, and strong conversion drivers close at the bottom.
The measurement problem nobody talks about
Even with the right creative and audience structure in place, most retail advertisers are still making decisions from a distorted picture. Part of that is how CPA gets reported. Part of it is which channels get invested in when pressure builds. Both come back to the same underlying problem: The numbers being used to make decisions don’t reflect what’s actually happening.
Every platform overclaims its contribution. Google takes credit for conversions. Meta takes credit for the same conversions. Reading both dashboards in isolation, without a neutral layer between them, makes double-counting almost inevitable. The more reliable approach is a blended CPA view: total spend across all channels divided by actual conversions from a source you control (your e-commerce platform or analytics tool, not the platforms). That’s the real number.
From there, incrementality testing tells you which channels are genuinely driving those conversions rather than just claiming them. For most retail advertisers, a realistic starting point is a simple geo holdout test: Pause spend in a small, matched region, keep everything else constant, and measure the difference in conversions from your own data. A clear test design with a success metric based on incremental lift, rather than platform-reported CPA, is what separates a meaningful result from one that simply confirms what the platform already wants you to believe.
The same distortion affects channel investment decisions. When CPA is under pressure, upper funnel spend, with elements such as awareness, video, and broader prospecting, is usually the first thing to get cut, because it doesn’t show an immediate return in the numbers. But that’s the wrong read. Lower-funnel channels like brand search, shopping, and retargeting only look efficient because they’re reaching people who are already close to buying. That pool doesn’t replenish itself. Upper funnel is what keeps new people flowing into it, so cutting it to protect short-term CPA accelerates the problem rather than solving it.
Because the effect isn’t immediate, the way to know it’s working is to track what moves first: branded search volume, direct traffic, engagement rates, and new user growth. These are early signals that demand is being built, and they will shift before conversion does. If they’re not moving, lower funnel CPA will eventually deteriorate, no matter how well the bottom of the funnel is optimized.
Bottom line
Sustained CPA pressure in retail is rarely a signal that something in-platform needs adjusting. More often it’s a signal that something earlier in the chain needs attention: the offer, the creative system, the audience structure, or the measurement layer telling you what’s actually working.
Start there. Focus on the parts of the system that matter most, and keep evolving as conditions change.
This story was produced by Brainlabs and reviewed and distributed by Stacker.
