Google Ads Ignores Your Size Profile - And You're Paying for It
If you're a fashion eCommerce brand spending £10k-£200k/month on Google Ads, this is going to feel uncomfortably familiar.
Picture This
T-shirt. XS, S, M, L, XL, XXL.
Only XS left.
Google: "Great, let's push it harder."
Your customer: a Large.
They click. Because they assume Google will show them something that fits.
They land. XS only.
They leave. You pay.
This isn't bad performance. This is paying for people to find out you don't have their size.
Why Does This Happen?
Because Google ignores your size profile.
It treats XS like it's its own product, not part of a size curve. So when XS is the only variant left in stock, Google sees a product that's "available" and starts spending.
So you're advertising to a fraction of the population who'd actually buy that size.
Everyone else clicks, realises, and leaves. Repeatedly.
The Core Problem
Google's Shopping algorithm has no concept of size distribution. It doesn't know that your core sizes drive the vast majority of sales while tail sizes account for a tiny fraction. It treats every in-stock variant as equally viable. This is a structural flaw, not a campaign setup issue.
The Real Cost
Let's make this tangible. A fashion brand with hundreds of styles, each in multiple sizes, will always have fragmented availability. At any given point, a significant portion of your catalogue has broken size runs - products where only tail sizes remain.
Every one of those products is live in Google Shopping. Every one is collecting clicks. Every click costs the same whether the shopper can buy or not.
The waste compounds. Those clicks don't just cost money directly - the resulting bounce rate signal feeds back to Google, telling it your products don't convert well. Which raises your CPCs across everything.
You're not just paying for wasted clicks. You're training Google to charge you more.
What Google Sees vs What's Actually Happening
The algorithm optimises within the data it has. It doesn't have size distribution data. It just sees a click, notes the outcome, and adjusts bids - usually in the wrong direction.
The Outlet Problem
Here's the thing most agencies miss entirely: broken sizing doesn't mean a product is dead. It means the product has changed commercial role.
A t-shirt with a full size run is a full-price product. The same t-shirt with only XS and XXL left? That's outlet stock. Clearance inventory. It belongs in a completely different part of your ad account.
What Should Actually Happen
Products with broken size runs should be separated into their own campaigns - treated as outlet or clearance stock. Penny bids. Aggressive ROAS targets. The goal shifts from "drive profitable sales" to "clear remaining inventory without burning full-price budget."
Instead, most accounts have these products sitting in the same campaigns as full-run stock, competing for the same budget, dragging down the same performance metrics. Google doesn't distinguish. Most agencies don't either.
We do. We've built a system that recognises when a product's size profile breaks and automatically changes how it's treated - separating clearance from commerce.
Is Your Agency Doing This?
Ask them. Specifically: "How do you handle size availability in our Shopping campaigns?"
If the answer involves the words "Google handles that" or "we pause out-of-stock products," they're not doing it. Pausing out-of-stock products is different from managing out-of-stock sizes within products that are technically still in stock.
This distinction matters. A product with one size left is technically "in stock." Google will advertise it. Your agency might not even notice. But your margin will.
And Google is still out there, aggressively scaling your last lonely XS.