Blended ROAS is always at the top of tracked Google Ads metrics, and for good reason. It's simple, and it gives teams a quick view of how much revenue the account is generating for every pound spent. But we want to give a small warning about blended ROAS, as it can also be misleading.
Any number that summarises an average across a whole account can hide what is really happening underneath. Some products may be driving strong, profitable growth, keeping that overall ROAS number looking great, and should have more budget given to them. Others may actually be costing you budget. When you're only looking at the average, you can miss both.
For e-commerce retailers, it's always important to look at the product level.
Why blended ROAS is useful (and you should keep it in your reports)
The blended ROAS number helps teams understand overall efficiency and gives stakeholders a quick performance snapshot. It can help with budget conversations and shows whether the account is broadly on target.
The problem isn't the metric itself; it's genuinely useful. The problem is when brands or agencies rely on it too heavily. Blended ROAS tells you what is happening across the account as a whole. It doesn't tell you which products created that result, which products were subsidised, or where the profit actually came from.
How an average value hides wasted budget
Imagine an account with a 600% ROAS. Looks great, doesn't it? But drop down to product-level analysis, and you might see a different story:
- A small group of bestsellers delivering 1,200% ROAS
- A larger group of products is breaking even
- A third of the budget is going to products below target
- Some SKUs are spending without converting at all
The average looks fine because the best products are carrying the weakest ones. If the ad budget were better invested in the top performers and cut from the weaker performing products, revenue could be sustainably higher.
This is where blended reporting becomes dangerous. It can hide a lot of inefficient spending because the top-line account still looks healthy, and you're missing out on easy ad revenue as a result.
Product-level performance is uneven
E-commerce catalogues are rarely balanced. Some products have strong demand, strong margins and strong conversion rates. Others are harder to sell, more price-sensitive or less visible in Google Shopping.
Even products in the same category can behave differently. A premium item may convert well from specific long-tail searches. A cheaper product may drive clicks, but struggle because CPCs leave little room for profit. A bestseller may need more investment, while a slow-moving SKU may need a different strategy entirely.
Blended ROAS cannot show these differences.
Why you should rethink basing your budget allocation on blended ROAS
If the ad budget is managed at too broad a level, and spending decisions are based on one overall score, products that don't generate profit can easily eat up the budget. When you rely on Google's automation over specialised AI like Bidnamic, it doesn't always understand your full commercial reality, and may optimise towards the conversion data it can see, which might be limited. It may not know which products have the best margins, which are overstocked, or which SKUs are strategically important to your business goals.
That's why product-level visibility matters, and it's worth repeating. You need to know:
- Which products are driving revenue
- Which products are driving profit
- Which products are wasting spend
- Which products deserve more visibility and budget
- Which products should be held back and get less budget
- Which products need feed or landing page improvements
Without this, your budget decisions are based on averages and effectively controlled by an automated system that doesn't understand which products are best at generating revenue from paid ads.
