ROAS vs ROI: what to measure in your ads

ROAS (return on ad spend) is revenue from ads divided by what you spent on the ads. ROI (return on investment) is profit after all costs divided by those costs. ROAS tells you how efficiently the ad budget turns into sales; ROI tells you whether the business actually made money. Measure ROAS to steer campaigns day to day, and ROI to decide whether advertising is worth doing at all and how much to spend.

The trap is treating a high ROAS as proof of profit. A campaign can show "4x ROAS" in the dashboard and still lose money once product costs, fees and management are counted. Below are both formulas with worked examples, how to find your break-even point, and what service businesses, which often don't sell online, should measure instead.

The formulas

ROAS = revenue attributed to ads / ad spend

ROI = (revenue − all costs) / all costs

"All costs" in ROI includes ad spend, the cost of the goods or service you delivered, payment fees, management fees, creative, software and any staff time tied to the campaign.

A worked example

The numbers below are invented to show the arithmetic, not benchmarks.

An online jewelry store spends $2,000 on Google Shopping in a month. The platform reports $8,000 in sales from those ads.

• ROAS = $8,000 / $2,000 = 4x (or 400%)

Now the full picture. The products sold cost $3,200 to make and ship. Payment processing takes $240. Management costs $1,000.

• Total costs = $2,000 + $3,200 + $240 + $1,000 = $6,440
• Profit = $8,000 − $6,440 = $1,560
• ROI = $1,560 / $6,440 ≈ 24%

Profitable, but much less exciting than "4x" suggests. If the store's margins were thinner, the same 4x ROAS could mean a loss.

Break-even ROAS: the number to know

Your break-even ROAS is the point where ad revenue just covers the ad spend and the cost of what you sold. Roughly:

Break-even ROAS = 1 / gross margin

If your gross margin (after product and delivery costs) is 50%, break-even ROAS is 1 / 0.5 = 2x. Below 2x, every sale from ads loses money on the first purchase. With a 25% margin, break-even is 4x, which is why low-margin stores struggle with ads that look healthy on paper.

Add management fees and tools on top, and your real target sits higher still. Once you know this number, you can set a target ROAS in Google Ads or Meta with confidence instead of guessing. The ad ROI calculator does the arithmetic for you.

Repeat customers change the picture

Judging ads only on the first purchase undervalues customers who come back. A cafe customer who buys once a week, a salon client who books every six weeks, a patient who stays for years: the first visit may barely break even and still be a great acquisition. Use customer lifetime value to decide how much you can spend to win a customer, especially for subscriptions and services with repeat visits.

What service businesses should measure

If you're a plumber, a law firm or a dental office, ad platforms don't see your revenue. They see calls and forms. ROAS isn't directly available, so measure a chain instead:

1. Cost per lead = ad spend / qualified leads (how to calculate it)
2. Close rate = customers / qualified leads
3. Cost per acquisition = ad spend / new customers
4. Revenue and profit per customer, from your own records
5. ROI = (profit from ad-sourced customers − all ad costs) / all ad costs

To get there, record the source of each lead in a CRM or even a spreadsheet, and mark which leads became paying customers and for how much. With that data, you can also import outcomes back into Google Ads and Meta so bidding learns from real sales rather than form fills. My guide to conversion tracking covers the setup, and end-to-end analytics connects ads, CRM and revenue in one place.

Attribution: why platforms all take credit

A customer sees your Instagram ad on Monday, searches your name on Google on Wednesday, clicks a search ad and buys. Meta may count the sale, and Google may count it too. Add the platform-reported revenue and you get more than you actually earned.

A few habits keep you honest:

• Compare total revenue in your own books with what platforms claim
• Watch what happens to total sales when you raise or cut a channel's budget
• Ask new customers how they found you
• Treat branded search and retargeting results with caution: some of those buyers were coming anyway

Common mistakes with both numbers

• Counting revenue before refunds and cancellations. Platforms record the order, not the return. Subtract refunds when you calculate ROI.
• Mixing time frames. Ad spend from March and revenue from deals that closed in June belong together. For long sales cycles, match spend to the period the leads came in, not the month the money arrived.
• Leaving out management and creative. They're real costs of the campaign. Without them, every channel looks better than it is.
• Comparing ROAS across very different products. A 3x ROAS on high-margin services and a 3x ROAS on low-margin retail goods are not the same result.
• Chasing a higher ROAS at any cost. Pushing the target up usually shrinks volume. Sometimes a slightly lower ROAS on a much larger budget earns more total profit.

Which number to watch when

• Daily and weekly: ROAS or cost per lead per campaign, to adjust bids, budgets and creative
• Monthly: cost per acquisition and close rate, to check lead quality
• Quarterly: ROI by channel, including all costs, to decide where next quarter's budget goes

If you'd like help setting this up, my management plans include reports every two weeks focused on leads, cost per lead and, where data allows, revenue. Google Ads management is from $1,000/month, Meta from $600/month. For a broader look at whether your marketing pays, read marketing ROI for non-data people or book a free 30-minute call.