How to Actually Measure ROI on Your SEO and Google Ads Campaigns
- Mike Percy
- Apr 15
- 4 min read
Updated: May 30
If you’re running Google Ads or SEO and still wondering “Is this actually working?” — you’re not alone.
Most service businesses rely on reports from their agency or marketing team that show “results.” But dig into those reports, and it’s often a sea of surface-level metrics:
Clicks
Impressions
ROAS
“Conversions” (usually undefined)
Sounds impressive. But here’s the uncomfortable truth:
None of those metrics tell you if your marketing is actually profitable.
To find that out, there’s only one number that matters — and most agencies don’t want to talk about it:
Gross Margin ROI.
This article shows you how to calculate it properly — using your actual costs, including agency fees — so you can stop guessing and start investing based on facts.
Why ROAS Is Misleading
ROAS (Return on Ad Spend) is the most commonly reported metric in digital advertising.
But here’s the catch: ROAS only shows revenue vs. ad spend. It ignores your cost to deliver the work — and your agency’s fee.
So if you're making $4,000 in revenue on a $1,000 ad spend, your ROAS looks like a win (4x). But if your cost to deliver those sales is $2,400 — and you're paying an agency $1,200 a month — you’re deep in the red.
⚠️ Here’s What That Really Looks Like:
Google Ads spend: $1,000
Gross revenue: $4,000
Gross margin: 40% → $1,600 gross profit
Agency fee: $1,200/month
Total marketing cost = $2,200
Gross Margin ROI = ($1,600 – $2,200) ÷ $2,200 = –27.2%
It looks like a 4x ROAS — but you’re losing money. That’s why Gross Margin ROI matters.
The Real ROI Formula
To calculate what your marketing is actually returning, use this:
(Gross Profit – Total Marketing Cost) ÷ Total Marketing Cost = Gross Margin ROI
Where “Total Marketing Cost” = Ad spend + agency fees + direct campaign costsAnd “Gross Profit” = Revenue from sales – direct variable costs
✅ Let’s Walk Through It:
Leads: 50
Close rate: 20% = 10 sales
Average sale: $1,000
Gross margin: 40% → $400 profit per sale
Total gross profit = $4,000
Google Ads spend = $2,000
Agency fee = $1,200
Total cost = $3,200
ROI = ($4,000 – $3,200) ÷ $3,200 = 25%
Now you have a real number you can make decisions on.
SEO ROI: The Long Game, Still Measurable
SEO is often misunderstood because the results take longer to show. But when calculated correctly, SEO can deliver long-term ROI that compounds over time.
Here’s how to model it out.
📊 SEO ROI Example (Including Agency Fee)
Keyword: “Brisbane physiotherapist”
Monthly search volume: 1,000
Ranking position: #1 → 27% CTR → 270 visits
Website conversion rate: 5% → ~13 leads
Sales conversion rate: 25% → ~3 sales
Average sale: $900
Gross margin: 50% → $450 profit per sale
Gross profit: ~$1,350
SEO agency fee: $1,200/month
Gross Margin ROI = ($1,350 – $1,200) ÷ $1,200 = 12.5%
Still positive. And over time, as rankings stick and more keywords drive traffic, that ROI increases — with no increase in monthly cost.
Google Ads ROI: Quick Feedback, but mind the conversion rates
Google Ads gives you more control and faster data — but it also has a higher spend ceiling, which makes margin tracking even more important.
Google Ads ROI Example (Including Agency Fee)
Impressions: 10,000
CTR: 5% = 500 clicks
CPC: $4 → $2,000 ad spend
Click-to-lead: 10% = 50 leads
Close rate: 20% = 10 sales
Average sale: $1,500
Gross margin: 40% → $600 per sale
Gross profit = $6,000
Agency fee = $1,200
Total cost = $3,200
ROI = ($6,000 – $3,200) ÷ $3,200 = 87.5%
Better than SEO short-term — but requires continued optimisation and oversight to maintain ROI.
Where to Get the Right Numbers
If you’re not already tracking these figures, here’s where to start:
Metric | Where to Find It |
Clicks, CTR | Google Ads, Search Console |
Website conversion rate | Google Analytics (Goals) |
Close rate | CRM, sales team input |
Average sale | Accounting software, POS |
Gross margin | Bookkeeper, accountant |
Agency fee | (You already know this one.) |
What to Ask Your Agency
If your agency is reporting ROAS, clicks, or impressions — but can’t tell you your actual commercial return — here are 5 questions to ask:
What’s my cost per lead AND cost per sale?
Are you calculating ROI using gross profit — not just revenue?
Is the agency fee included in those numbers?
Are we tracking lifetime value from these leads?
What’s improving — clicks or actual margin ROI?
If they can’t answer clearly, it’s time to reassess.
Final Thought: You Deserve a Marketing Model That Pays You Back
At Substrate Media, we don’t report fluff. We don’t bury results in jargon. And we don’t run campaigns that can’t justify their cost.
If you’re going to invest in marketing — especially SEO or Google Ads — you deserve to know what you’re getting, what it’s costing, and what it’s returning.
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