ROAS Is a Ratio. Here's Why It Lies to DTC Brands
ROAS tells you revenue per pound spent. It doesn't tell you profit. And that distinction is destroying margins across ecommerce.
A 5x ROAS sounds excellent. £5 back for every £1 spent. But here's the question nobody asks: how much of that £5 was profit?
If your average margin is 40%, that £5 in revenue becomes £2 in gross profit. Subtract your £1 ad cost and you've made £1. A 5x ROAS delivered a 1x return on actual profit.
ROAS measures revenue efficiency. It tells you nothing about whether that revenue covered your costs, funded your operations, or contributed to growth.
The Maths That Gets Ignored
Let's work through a real example:
Ad spend
£10,000
Revenue (5x ROAS)
£50,000
COGS (60%)
-£30,000
Gross profit
£20,000
Ad spend deducted
-£10,000
Contribution margin
£10,000
That 5x ROAS delivered a 1x contribution margin multiple. Still profitable, but nowhere near as impressive as the headline number suggested.
Now imagine the same scenario with 30% margins instead of 40%:
Gross profit (30%)
£15,000
Ad spend
-£10,000
Contribution margin
£5,000
Same 5x ROAS. Half the actual profit. The metric didn't change. The commercial reality did.
Why DTC Brands Fall for This
ROAS Is Universal
Every platform reports it. Every agency talks about it. It becomes the default success metric because everyone understands the number, even if they don't understand what it means commercially.
Margin Variability Gets Hidden
Most brands have wildly different margins across their catalogue. A 5x ROAS on a 60% margin product is completely different from a 5x on a 25% margin product. ROAS treats them identically.
The Number Is Always Positive
A 2x ROAS still sounds like you're doubling your money. You're not. If your margin is 40%, a 2x ROAS means you're losing 20p on every pound spent.
The Break-Even ROAS Calculation
Every brand has a break-even ROAS. It's the minimum return needed to cover costs before any profit is made.
Break-Even ROAS = 1 ÷ Gross Margin
- • 50% margin = 2x break-even ROAS
- • 40% margin = 2.5x break-even ROAS
- • 30% margin = 3.3x break-even ROAS
- • 25% margin = 4x break-even ROAS
Anything below break-even and you're paying to acquire customers at a loss. That can be strategic for new customer acquisition, but it's rarely understood clearly.
The POAS Alternative
Profit on Ad Spend (POAS) solves this by measuring gross profit returned per pound spent, not revenue. It requires knowing your margins at the product or order level, but it tells you what actually matters: did this campaign make money?
ROAS Focus
- • Revenue generation
- • Volume at any margin
- • Platform-friendly metrics
- • Easy to compare across brands
POAS Focus
- • Profit generation
- • Commercial sustainability
- • SKU-level clarity
- • Actual business health
What This Means for Your Account
If you're optimising for ROAS alone:
- Your highest-revenue products might be your least profitable
- Campaigns "performing well" could be eroding contribution margin
- Scaling what looks successful could accelerate losses
- Low-ROAS products with high margins might be underinvested
The fix isn't complicated. It's visibility. Know your margins, calculate your break-evens, and stop treating ROAS as a proxy for profit.
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