ROAS vs POAS — why you’re optimising for the wrong number
A 4x ROAS campaign can lose money. A 2x ROAS campaign can be your most profitable. The difference is margin — and the metric that accounts for it.
Jakob Sperber
Director
Marketing
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ROAS is the default performance metric in ecommerce advertising. Every agency report, every platform dashboard, every Slack update leads with it. “We hit 4x ROAS this week.”
But ROAS measures revenue return. Not profit return. And revenue is a terrible proxy for profit when different products have different margins, different shipping costs, and different return rates.
POAS — Profit on Ad Spend — fixes this. It’s not a new concept, but it’s one that most brands still aren’t using. And the ones that switch usually discover their “best” campaigns aren’t what they thought.
ROAS: what it actually measures
ROAS = Revenue ÷ Ad Spend
If you spend $1,000 on ads and generate $4,000 in revenue, your ROAS is 4x. Sounds great. But what if those sales were your lowest-margin products with a 40% COGS and $12 shipping? Your actual gross profit on that $4,000 might be $1,400 — a 1.4x return on what you actually keep.
ROAS treats a $100 sale of a high-margin product the same as a $100 sale of a low-margin product. It doesn’t know the difference. And if you’re optimising campaigns to maximise ROAS, the algorithm is chasing revenue — not profit.
POAS: what you should measure instead
POAS = Gross Profit ÷ Ad Spend
POAS replaces revenue with gross profit (or CM2 if you want to be precise about it). Now you’re measuring how much margin each ad dollar generates — not just how much top-line revenue.
A worked example
You run two campaigns last month:
Campaign A — bestseller product (high margin):
Ad spend: $3,000
Revenue: $9,000 (ROAS: 3x)
COGS + variable costs: $3,150 (35%)
Gross profit: $5,850
POAS: 1.95x
Campaign B — discounted bundle (low margin):
Ad spend: $3,000
Revenue: $12,000 (ROAS: 4x)
COGS + variable costs: $7,800 (65%)
Gross profit: $4,200
POAS: 1.4x
Campaign B has better ROAS (4x vs 3x). Most agencies would scale Campaign B and pull back on Campaign A. But Campaign A generates $1,650 more profit on the same spend.
ROAS says Campaign B wins. POAS says Campaign A wins. The profit says POAS is right.
Why agencies default to ROAS
Three reasons:
It’s what ad platforms report. Meta, Google, and TikTok all surface ROAS natively. POAS requires external margin data, which means extra setup.
Agencies don’t have margin data. Most agencies don’t ask for your COGS or variable costs. They optimise with the data they have, which is revenue-based.
ROAS is always a bigger number. A 4x ROAS looks better in a client report than a 1.4x POAS, even though the POAS number is more honest about business performance.
How to implement POAS
Calculate gross profit per product or product category. Revenue minus COGS minus variable costs (shipping, processing, pick & pack). This is your CM2 from the unit economics stack.
Pass profit data to your ad platform or analytics tool. Tools like Triple Whale, Northbeam, or even a custom Google Sheets integration can ingest margin data and calculate POAS alongside ROAS.
Set POAS targets instead of ROAS targets. A 1.5x POAS means every $1 of ad spend generates $1.50 of gross profit — $0.50 to cover fixed costs and profit. Adjust based on your fixed cost structure.
Optimise campaigns for profit, not revenue. Shift budget toward campaigns with high POAS, even if their ROAS looks lower. Kill campaigns with high ROAS but low POAS — they’re generating revenue at the expense of margin.
When ROAS still works
If you sell a single product at a single price with consistent margins, ROAS and POAS will trend in the same direction. The distinction matters most when you have:
Mixed-margin product catalogues
Bundles or discounted offers with different unit economics
Variable shipping costs across product weights
Different return rates by product category
If any of these apply to you — and they apply to most brands scaling past $1M — POAS is the metric that tells you the truth.
The bottom line
ROAS measures effort. POAS measures outcome. You don’t pay suppliers, staff, and rent with revenue — you pay them with margin. Optimise for the thing that actually keeps the business running.
