ROAS Is Lying to You: Optimize for Profit (POAS), Not Revenue

Your ROAS is 500%. Are you profitable? The honest answer is: it depends. ROAS tells you how much revenue an ad dollar brings in. About your profit it says nothing. This is exactly where small-business accounts quietly lose money while the dashboard looks green.

I see it regularly in audits: the campaign optimizes cleanly toward a high revenue ROAS, and still less is left at month-end than expected. The reason is almost always the same. Google knows your revenue, but not your margin.

What Is ROAS, and What Does It Actually Measure?

ROAS stands for Return on Ad Spend. The formula is simple:

ROAS = revenue from ads / ad spend

Per Google Ads Help, the conversion value ROAS is built on is, by default, the order value you pass through conversion tracking. At $5,000 revenue from $1,000 ad spend, your ROAS is 500% (or 5.0 as a ratio).

The problem hides in the word revenue. ROAS counts what comes into the till at the top, not what’s left at the bottom. Cost of goods, shipping, returns, payment fees: all of it is invisible to ROAS.

The ROAS Illusion: Why 500% Says Nothing About Profit

Two shops, same ROAS, completely different outcome:

	Shop A (jewelry)	Shop B (electronics)
Revenue from ads	$5,000	$5,000
Ad spend	$1,000	$1,000
ROAS	500%	500%
Net margin before ads	60%	12%
Contribution margin (revenue × margin)	$3,000	$600
Profit after ad spend	+$2,000	−$400

Shop A makes money. Shop B loses money at an identical ROAS. The revenue ROAS gave both the same success signal, and for one of them it was wrong. Smart Bidding would even push Shop B harder, because the algorithm optimizes toward the conversion value you feed it, and that value is revenue.

How to Calculate Break-even ROAS

Break-even ROAS is the point where your contribution margin exactly covers your ad spend. The formula is pleasingly short:

Break-even ROAS = 1 / net margin

An example at a 35% margin: 1 / 0.35 = 2.86. So you need 286% ROAS just to land at zero. Anything below that loses money, even though a ROAS of 280% looks decent on the dashboard.

The thinner the margin, the more brutal the threshold:

Net margin	Break-even ROAS	You profit above
60%	167%	anything over 167%
35%	286%	anything over 286%
20%	500%	anything over 500%
10%	1,000%	anything over 1,000%

This one number belongs in every account before you set a ROAS target. Set a 400% target ROAS on a 12% margin and you’ve hard-wired the loss into your bidding.

What Belongs in Your Profit Math?

Contribution margin is what’s left of revenue after variable costs. What counts depends on the business model.

E-commerce:

• Cost of goods or production
• Shipping and packaging
• Returns (often the underestimated line item)
• Payment fees
• Sales tax (if the value you pass is gross)

Service and B2B:

• Labor per job
• Materials and travel
• Follow-up and warranty work

Only once these are in do you talk about profit instead of revenue. And this is exactly the math Google won’t do for you.

POAS Over ROAS: Optimize for Profit

POAS stands for Profit on Ad Spend. Instead of revenue per ad dollar, POAS measures contribution margin per ad dollar:

POAS = contribution margin / ad spend

The difference matters when your products carry different margins. A shop with 600 variants, some at 8% and some at 50% margin, can’t be steered sensibly by a single revenue ROAS. The algorithm then pushes budget toward high-revenue but low-margin products, because they make the ROAS look pretty.

POAS flips that: the bidding learns which products bring real profit, not just revenue. Tools like ProfitMetrics calculate the contribution margin per order and pass that value back to Google as the conversion value, instead of the gross cart total.

How to Track Profit Instead of Revenue

There are three ways, and they differ mainly in effort and accuracy.

1. Manually via net margin. Instead of passing revenue as the conversion value, you pass revenue times your average net margin. Quick to set up, but inaccurate once your per-product margins swing widely.
2. Automatically through ProfitMetrics. The real contribution margin per order flows back as the conversion value. Accurate, but it comes with setup effort and a running cost.
3. Offline conversion import with corrected values. Useful for lead businesses where the real value is only known after the deal closes.

For any of this to land usable numbers, your tracking has to be clean. If 30 to 40% of conversions never get measured because of missing consent or ad blockers, you’re calculating profit on a leaky base. How to set that up so it holds is in the Server-Side Tracking post, and which tracking mistakes otherwise distort the conversion value is in the Google Ads conversion tracking issues post.

FAQ

What is a good ROAS?

There’s no universally good ROAS. A good ROAS is any ROAS above your break-even ROAS, and that depends solely on your net margin. At a 50% margin, 250% ROAS is already profitable; at a 10% margin you’re still losing money even at 800%. That’s why the question can’t be answered without your margin.

How do I calculate break-even ROAS?

Divide 1 by your net margin. At a 25% margin that’s 1 / 0.25 = 4.0, which is 400% ROAS. Only above that do you make money. Use the margin before ad spend, or you’ll be counting the ad cost twice.

What’s the difference between ROAS and POAS?

ROAS measures revenue per ad dollar; POAS measures contribution margin (profit before ads) per ad dollar. ROAS is simpler but blind to your margin. POAS is more honest but needs per-product margin data. With uniform margins ROAS often does the job; with widely different margins only POAS leads to sensible bidding decisions.

Do I need ProfitMetrics to track profit?

No. As a first step it’s enough to pass revenue times your average net margin as the conversion value. ProfitMetrics pays off when your per-product margins swing widely and the average gets too rough. Then the exact per-order contribution-margin calculation earns its keep.

Why doesn’t Google Ads show profit?

Because Google doesn’t know your cost side. Cost of goods, shipping, returns and fees don’t exist inside Google Ads. Google can only work with the conversion value you pass. Pass revenue, and it optimizes for revenue. Pass contribution margin, and it optimizes for profit.

Your Next Steps

First, calculate your break-even ROAS. That single number decides whether your current ROAS targets can even be profitable. Second, work out whether an average margin figure is enough, or whether your product margins differ so much that you should move to POAS.

If you want to know whether your account optimizes for revenue or profit, and whether your tracking delivers the right values, let’s go through it in a free initial consultation. Drop me a line about what you’re working with, and we’ll find where your real lever is. The most common structural mistake behind all this I cover in the 5 most common Google Ads mistakes for small business post.