How to Stop Google Ads Spending on Low-Margin SKUs

Low-margin products love Google Ads. They often convert well because they're cheaper and lower-risk for buyers. The algorithm sees conversions and bids harder. You see ROAS and celebrate. But the contribution margin tells a different story.

Identifying the Problem SKUs

First, you need visibility. Export your SKU-level Google Ads data and match it against your margin data:

• • Pull ad spend, conversions, and revenue per SKU
• • Map each SKU to its contribution margin
• • Calculate contribution profit: (Revenue × Margin %) - Ad Spend
• • Rank by contribution profit (not ROAS)

You'll likely find a cluster of products that drive significant spend but negative or minimal contribution profit.

The ROAS Trap

Here's why ROAS misleads you. Consider a £30 product with 20% margin (£6 contribution):

6x ROAS looks excellent. But you made £1. Now consider you spend 10% more (£5.50) and ROAS drops to 5.5x. You just went negative.

Low-margin products have no room for error. Small changes in CPC or conversion rate flip them from marginal to loss-making.

Tactics to Stop the Bleed

1. Exclude Entirely

For products that can't be profitable at any reasonable CPC, exclude them from all paid activity. Use custom labels to mark them as "exclude" in your feed.

2. Set Appropriate Targets

If the product needs 8x ROAS to be profitable, set an 8x target. Yes, volume will drop. That's the point. You're trading unprofitable volume for profitable sales.

3. Cap Budgets

Segment low-margin products into their own campaign with a strict budget cap. This limits downside while still capturing the genuinely efficient conversions.

4. Use Negative Keywords

For Search campaigns, add negative keywords for broad, expensive terms that drive traffic to low-margin products. Be surgical about what searches you allow.

5. Review Regularly

Margin changes. Supplier costs increase. Shipping gets more expensive. A product that was profitable six months ago might not be today. Quarterly margin reviews are essential.

The Conversation with Leadership

Cutting low-margin SKUs from Google Ads will reduce reported ROAS and conversion volume. Your dashboard will look worse. You need to prepare stakeholders for this.

Show the contribution margin analysis. Explain that higher ROAS on unprofitable products isn't success. Get buy-in before making changes, or you'll be defending yourself with spreadsheets after the fact.