Switching to POAS Bidding in Google Ads The Practical Guide Stop Chasing Revenue:

Let's face it, in this game, it is far too easy to get caught up in the "buzz" of high revenue numbers. You see those big figures on the dashboard—thousands of pounds rolling in—and it feels like you’re winning. It feeds the ego, doesn't it? But I reckon a lot of business owners are looking at record-breaking sales while their actual bank balance is telling a very different, much grimmer story.

The culprit, more often than not, is ROAS (Return on Ad Spend).

It’s the standard metric everyone uses—agencies love it because it’s easy to report—but frankly, it’s often just vanity. It asks, "For every quid I spend, how much revenue do I get back?". It sounds sensible enough on paper. The problem is, revenue isn't profit. If you’re selling low-margin goods, a "successful" campaign with a high ROAS could actually be bleeding you dry, and you wouldn't even know it until the accountant calls.

That’s why I believe the smart move—the one that actually makes sense if you want to be doing this in five years' time—is shifting to POAS (Profit on Ad Spend). It’s about satisfaction, really. It's knowing that for every pound you put in, you’re getting actual profit out to pay the mortgage, not just turnover to pay the supplier.

Part 1: The "Un-Learning" Phase (Why Revenue is a Liar)

Before we get into the technical bits—which can be a bit of a headache, I won't lie—we need to look at the maths. I suppose it's a bit of a reality check.

The fundamental flaw with ROAS is that it treats all revenue as equal. But you and I know that £100 from a high-margin product is worth a hell of a lot more than £100 from a loss leader.

Imagine you have two products in your catalogue:

• Product A (The Revenue Driver): Sells for £100. It costs you £90 to buy, ship, and tax. Your margin is a tenner.
• Product B (The Profit Maker): Sells for £50. It costs you £10. Your margin is £40.

Now, watch what happens in Google Ads.

If the algorithm spends twenty quid to sell Product A, your ROAS looks fantastic—500%. Agencies would be high-fiving over that. But do the maths: you made £10 margin and spent £20 on ads. You’ve lost a tenner.

If it spends that same twenty quid to sell Product B, your ROAS looks lower—250%. But you’ve made £40 margin minus £20 ad spend. You’ve made £20 profit.

A ROAS-focused algorithm is lazy. It will chase Product A every time because it's the path of least resistance to high revenue figures. It doesn't care about your bank account; it just cares about hitting the target you gave it. It’s a bit of a toss-up if you rely on that, really.

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The "Break-Even" Reality Check

You need to know your numbers. If you don't know your break-even point—the exact ROAS where you stop losing money—you're flying blind. And let's be honest, hope is not a strategy.

Here is a look at what ROAS you actually need just to keep the lights on.

Part 2: The Strategy (The "Trojan Horse" Method)

Now, I’m not sure if you’ve had a look around the dashboard lately, but there isn’t a "POAS" button in Google Ads. Google hasn't built one, which is typical—they'd rather you spent budget on revenue volume.

So, we have to use a bit of a workaround—a "Trojan Horse," if you like.

We are essentially going to trick the system. We aren't changing the bidding strategy itself; we are changing the fuel we put into the engine.

1. Old Way: Website tells Google, "This order was worth £100" (Revenue).
2. New Way: We intervene. We calculate the profit in the background (£100 revenue - £60 costs = £40). We tell Google, "This order was worth £40."

We still use the "Target ROAS" bidding strategy. But because the data going in is profit, the algorithm optimizes for profit. It thinks it's maximizing revenue, but it's actually maximizing your bottom line. It’s pragmatic. We’re using their sophisticated machine to do what we want.

Part 3: Implementation (The "Automated" Path)

To be honest, unless you love spreadsheets more than your family—or you've got way too much time on your hands—I wouldn't recommend doing this manually. If you're doing 50 or more orders a month, the manual route is just a nightmare waiting to happen. Human error creeps in, you forget to upload a file one day, and the whole thing goes to pot.

I reckon it’s worth paying a few quid for a tool that handles the data connection for you. It saves the hassle, and frankly, my time is worth more than the subscription cost.

The Tools That Actually Work:

• ProfitMetrics: Does exactly what it says on the tin. Solid bit of kit.
• Reaktion: Good if you like visualising the data, a bit more "dashboardy".
• Pixel Manager for WooCommerce: If you're on Woo, this handles the heavy lifting well.

The Workflow:

1. Connect: Link the app to your store.
2. Sync Costs: This is the hard part—you have to enter the Cost of Goods Sold (COGS) for every single product in your backend. If you miss this, well, it's shit, because the system assumes 100% profit and bids too high. You need to be disciplined here.
3. Create Goal: The app will send a new conversion called "POAS" or "Gross Profit" to Google Ads.

Part 4: Implementation (The "Manual" DIY Path)

If you're just starting out, or maybe you just enjoy the pain of doing it yourself, you can do it for free. It’s a bit of a slog, but if you're meticulous, it works.

For Shopify Users

1. The Digital Luggage Tag (GCLID): You need to capture the 'Google Click ID'. This is the unique code Google attaches to every ad click. You'll need to edit your theme.liquid code to save this ID into a cookie.
2. Pass to Cart: Then, you need to pass that cookie value into a hidden field in your cart attributes so it appears on your order export. If coding isn't your vibe, grab a cheap app just to handle this part.
3. Export & Calculate: Export your orders to a CSV. Add a column for Profit (Total Sales - Cost of Goods - Shipping).
4. Upload: Go to Google Ads > Goals > Uploads. Map your new Profit column to the "Conversion Value" field.

For WooCommerce Users

1. Get the Data: WooCommerce is a bit annoying because it doesn't store costs by default. You’ll need a plugin like "Cost of Goods for WooCommerce".
2. Capture the ID: You need to grab that GCLID. Use a plugin like "HandL UTM Grabber"—it just works.
3. The Export: Export your orders, ensuring you include the GCLID and the Cost fields.
4. The Spreadsheet Work: Calculate the profit in Excel (Revenue - Cost - Shipping = Value). Save it and upload it to Google.

Part 5: The "Gotchas" (Handling Overheads)

This is where I think a lot of people hit a wall. They ask, "What about my rent? What about staff wages? Shouldn't I deduct those?"

Do NOT include rent, wages, or fixed overheads in the data you send to Google.

It sounds counter-intuitive, I know. But think about it: your rent is £1,000 whether you sell one widget or a thousand. If you try to deduct a "slice" of rent from every single order, the maths fluctuates wildly depending on your volume. It confuses the algorithm, and you end up with a mess—total bollox, really.

The Fix: Contribution Margin

You feed Google your Gross Profit (Revenue minus COGS and Shipping). This is your "Contribution Margin"—the money left over to pay the bills.

Then, you adjust your Target to cover the rest.

Image Prompt 6: The Contribution Bucket

Visual Style: Diagrammatic illustration.

Description: A bucket labeled "Business". Water labeled "Gross Profit" is being poured in from the top (from Ads). There is a tap at the bottom labeled "Fixed Costs (Rent/Wages)" letting water out. The water remaining in the bucket is labeled "Net Profit".

Purpose: To illustrate that Ads fill the bucket (Gross Profit), they don't pay the rent directly per order.

The Calculation Example:

Let's say your Gross Profit is decent, but you have heavy overheads (expensive office, big team).

1. Look at your P&L. Let's say Fixed Costs eat up 30% of your Gross Profit.
2. This means for every £1 of profit Google brings in, 30p goes to bills.
3. You need to bid more conservatively.
4. Take your Break-Even POAS (1.0) and divide it by (1 - 0.30).
   • 1.0 / 0.70 = 1.43
5. Your new "Safe Target" is 143% POAS. You need to make £1.43 profit for every £1 spend to cover the lights and wages.

Part 6: The "Safe Switch" Protocol

Don't just flip the switch tomorrow. That’s a recipe for disaster. I’ve seen campaigns crash because people changed targets too fast, and frankly, it's painful to watch a good account die overnight.

Phase 1: Observation (Weeks 1-3)

Set up the "Profit" conversion as a Secondary action in Google Ads.

Just watch it. Don't touch the bidding.

At the end of the month, look at the columns. Does the "Profit" reported in Google match your backend numbers? If it's miles off, check your COGS. If it matches, you're good to go.

Phase 2: The Flip (Week 4)

Once you trust the data, make "Profit" your Primary conversion action.

Set your old "Revenue" conversion to Secondary (so you can still see it for comparison).

Phase 3: The Target Adjustment (Crucial)

This is the most important bit. You must lower your percentage target.

• Old World: You targeted 400% ROAS (Revenue).
• New World: If you leave the target at 400%, Google will try to get £4 of profit for every £1 spend. That's likely impossible. Your ads will stop spending entirely.
• The Fix: Calculate your historical POAS from the last month (Total Profit / Ad Spend). If it was 150%, set your target to 150%.

Conclusion

At the end of the day, moving to POAS is about stability. It stops the guesswork. It means you can scale up those winning products without worrying if you’re secretly losing money on the back end, and you can cut the losers that are just churning cash.

It takes a bit of effort to set up—well, more than a bit, it can be a faff—but I reckon it's the only way to run ads if you want to be here for the long haul. You get to sleep better knowing the money in the dashboard is money you actually get to keep.

Give it a go, but take your time with the data first. Don't rush it.

Stevie Morris

PPC Consultant Involved in online marketing for the last 25 years first with SEO , Web Development and now for the last 12 years focusing on  PPC & Google Ads