If you're checking your Meta Ads Manager every morning watching ROAS bounce around, you're optimising for the wrong thing.

Here's the truth: attribution is broken.

When you're running Meta + Google + Email, the same sale gets claimed by multiple platforms. You can't add up those ROAS numbers and expect them to reflect reality.

So what should you track instead?

📊 The 3 Metrics That Tell the Real Story

1. MER (Marketing Efficiency Ratio)

Total Revenue ÷ Total Marketing Spend (all channels)

MER is the only metric that can't lie. It doesn't care which platform gets credit. It just asks: "Did we make more money than we spent on marketing?"

Target: 3.5x to 4.5x for most eCommerce businesses

MER cuts through attribution mess and shows true marketing efficiency across your entire stack.

2. CAC (Customer Acquisition Cost)

Total Marketing Spend ÷ New Customers Acquired

CAC tells you what each customer actually costs to acquire across all channels.

The critical question: Can you afford this CAC relative to your Average Order Value?

Rule of thumb: Keep CAC under 33% of your AOV, ideally 25%

3. AOV (Average Order Value)

Total Revenue ÷ Total Orders

AOV is the other side of the profitability equation. When CAC rises, increasing AOV saves you.

Boost AOV through:

• Bundles and multi-buy offers
• Free shipping thresholds
• Checkout upsells
• Promoting higher-ticket products

The healthier your AOV relative to CAC, the more profitable your ads.

🌐 Why This Matters When You're Multi-Channel

When a customer sees your Instagram ad, Googles your brand, gets your email, then buys via a Google ad, every platform claims credit for the sale.

Meta says 4x ROAS. Google says 5x ROAS. Your email platform counts a conversion.

But you can't count the same sale three times.

MER solves this. It measures the whole system, not individual platform claims.

📅 Your New Weekly Habit

Stop: Checking ROAS daily across platforms

Start: Tracking these three metrics every Monday

• MER → Is overall marketing efficient?
• CAC → Can I afford to acquire customers?
• AOV → Are customers buying enough per order?

If MER is healthy, CAC is sustainable, and AOV is growing, your business is profitable regardless of what platform dashboards say.

🎯 When Platform ROAS Is Actually Useful

Use platform ROAS for:

• Comparing campaigns within the same platform
• Identifying winning creative

Don't use it for:

• Measuring true profitability (use MER)
• Comparing performance across platforms (attribution overlap)
• Strategic business decisions (use CAC/AOV)

✅ The Bottom Line

Track these three metrics weekly:

• MER → Overall marketing efficiency
• CAC → Cost to acquire each customer
• AOV → Revenue per order

Keep MER above 3.5x and CAC under 33% of AOV, and you'll have a profitable business.

Simple, honest, actionable.

This tracking system is exactly what we build in How We Convert. Real metrics. Real profitability. No attribution guesswork.

🎁 The Freebie

Here's a simple calculator spreadsheet to help you track your weekly MER without needing a maths degree.

Thanks for reading,
Michael from How We Convert 🤓