ROI vs ROAS: The Difference and When to Use Each

ROAS (return on ad spend) divides the revenue from ads by the ad spend, so it tells you how much revenue each unit of ad spend brought back. ROI (return on investment) compares profit with the total cost, so it tells you whether the activity made money after every expense. A campaign can have a high ROAS and still lose money once product costs, fees and staff time are counted. Use ROAS to manage and compare ad campaigns day to day. Use ROI to decide whether a channel, campaign or project is worth the investment overall.

This post sets out the two formulas side by side and works through two campaigns where the one with the higher ROAS has the lower ROI. It explains break-even ROAS, which links the two, and covers common reporting mistakes, including one in a widely used ad platform's own column names. The campaign figures are illustrative; the formulas are standard.

The formulas

Table: ROI and ROAS compared

	ROAS	ROI
Formula	Revenue from ads ÷ ad spend	(Return − investment) ÷ investment × 100
Uses	Revenue	Profit
Costs counted	Ad spend only	Everything: ad spend, product costs, fees, tools, staff time
Usually written as	A ratio (4:1, or 4) or a percentage (400%)	A percentage (25%)
Break-even point	Depends on your margin (see below)	0%
Best for	Optimising campaigns, ad groups and bids	Deciding whether an investment is worth making

Google Ads uses the same ROAS definition for its bidding. Its help article on target ROAS describes it as the average conversion value you want for each unit you spend, with the example "$5 USD in sales ÷ $1 USD in ad spend x 100% = 500% target ROAS".

For ROI, "return" should mean the profit the investment produced. Using revenue as the return is the most common mistake, and it can make a losing campaign look excellent, as the worked example shows.

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What you need before you calculate

• Ad spend for the period, from the ad platform.
• Revenue attributed to the ads, from the ad platform or your analytics, using a stated attribution model.
• Your gross margin: the share of revenue left after the direct cost of the products or service sold.
• Other campaign costs: agency or freelancer fees, creative production, tools, discounts and staff time.
• A fixed period, applied to every figure, so you are comparing like with like.

Consistent tracking matters more than the formula. If your campaign links use inconsistent UTM tags, revenue ends up attributed to the wrong source; our guide to UTM parameters covers a naming scheme that keeps reports clean.

Worked example: the higher ROAS is not the better campaign

An illustrative online shop runs two campaigns in the same month:

Table: Two illustrative campaigns

	Campaign A	Campaign B
Ad spend	$2,000	$1,000
Revenue from the ads	$8,000	$3,500
Gross margin on the products sold	40%	60%
Other costs (agency fee, creative)	$800	$200
ROAS	4.0 (400%)	3.5 (350%)
Gross profit (revenue × margin)	$3,200	$2,100
Total cost (ad spend + other)	$2,800	$1,200
Net profit	$400	$900
ROI	14.3%	75.0%

Judged by ROAS, Campaign A wins. Judged by profit, Campaign B made more than twice as much money on half the spend, because it sold higher-margin products and cost less to run. If the shop moved budget from B to A based on ROAS alone, it would earn less.

The calculation for Campaign A, step by step:

• ROAS = $8,000 ÷ $2,000 = 4.0.
• Gross profit = $8,000 × 40% = $3,200.
• Total cost = $2,000 + $800 = $2,800.
• ROI = ($3,200 − $2,800) ÷ $2,800 × 100 = 14.3%.

Now the common mistake. If you use revenue as the return, Campaign A's "ROI" becomes ($8,000 − $2,800) ÷ $2,800 = 185.7%. That figure ignores the cost of the products sold and overstates the result more than twelvefold.

You can check each step with the ROAS calculator and the ROI calculator. Enter gross profit, not revenue, as the return in the ROI calculator.

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Break-even ROAS: the bridge between the two

Break-even ROAS is the ROAS at which ad revenue only just covers the product costs and the ad spend. With gross margin written as a decimal:

Break-even ROAS = 1 ÷ gross margin

Table: Break-even ROAS at different margins

Gross margin	Break-even ROAS	Meaning
20%	5.0	You need $5 of revenue per $1 of ads just to break even
25%	4.0	$4 per $1
40%	2.5	$2.50 per $1
60%	1.67	$1.67 per $1
80%	1.25	$1.25 per $1

Campaign A's ROAS of 4.0 is above its break-even of 2.5, so it covers product costs and ad spend. But break-even ROAS ignores other costs, which is why A's $800 of fees took most of its profit. If you have significant non-ad costs, add them to the ad spend before calculating the ROAS you need, or track ROI as well.

Not sure of your margin? The profit margin calculator works it out from cost and price, and also shows markup, which is often confused with margin.

When to use each

Table: Choosing a metric

Question	Metric
Which ad group or keyword brings the most revenue per unit spent?	ROAS
What target should automated bidding aim for?	ROAS, set above break-even
Is this channel profitable once everything is counted?	ROI
Should we hire an agency or buy a tool for this campaign?	ROI
How do paid ads compare with email or SEO?	ROI (ROAS does not apply to unpaid channels)
Should we raise the budget next month?	Both: ROAS to see if efficiency holds, ROI to see if profit grows

A practical reporting rhythm is ROAS weekly for campaign management, and ROI monthly or quarterly for budget decisions.

Setting up the numbers on a WordPress site

Both metrics are only as good as the revenue and cost data behind them. On a WordPress site, that usually means connecting three sources:

• Revenue. For a shop, the order totals in WooCommerce or your shop platform are the most reliable figure. For lead generation, give each lead a value, such as average deal size × close rate, so conversions have a monetary value.
• Attribution. Tag every campaign link consistently. The UTM builder creates tagged URLs, so analytics can tie orders and leads back to the campaign that produced them. Mark purchases or form submissions as key events in Google Analytics 4 so they appear in acquisition reports.
• Costs. Ad spend comes from each platform. Keep other costs, such as fees, tools, creative and staff time, in a simple spreadsheet by campaign and month, so ROI can be calculated without guessing.

Conversion rate sits between the two metrics. If ROAS drops, check whether fewer visitors are buying (conversion rate) or each order is worth less (average order value) before changing bids. The conversion rate calculator also works out cost per conversion when you enter ad spend.

Small sites often lack enough conversions for stable weekly figures. If a campaign has only a handful of sales a week, judge ROAS and ROI over a month or a quarter rather than reacting to every swing.

Watch the labels in your reports

Platforms do not always use these terms consistently. Google Ads' help article on conversion data describes its "Conv. value / cost" column, conversion value divided by cost, as an estimate of return on investment. By the definitions here, that column is ROAS, because it uses conversion value (usually revenue) and only ad cost. Treat any column called ROI in an ad platform as revenue-based unless you have loaded profit values into it.

Check your numbers

• Confirm the period is the same for spend, revenue and costs.
• Check attribution. Compare platform-reported revenue with your shop or CRM. Platforms count conversions under their own rules, and their totals often add up to more than your real sales.
• Use profit for ROI, never revenue.
• Include all costs in ROI: fees, tools, creative, discounts and refunds.
• Recalculate break-even ROAS whenever your margins or prices change.
• Write down the definitions you use in reports so others interpret them the same way.

Common mistakes

• Calling a revenue-based ratio "ROI".
• Comparing ROAS across products with very different margins.
• Setting a target ROAS below break-even and growing a loss-making campaign.
• Leaving agency fees, tools or staff time out of ROI.
• Mixing time periods, such as one month of spend against six weeks of revenue.
• Ignoring refunds and returns, which reduce real revenue.
• Judging brand or awareness campaigns on short-term ROAS alone, when their returns arrive later.

Troubleshooting

Table: ROI and ROAS problems

Symptom	Likely cause	Fix
Strong ROAS, but the business is not making money	Margins too thin, or large non-ad costs	Calculate break-even ROAS and full ROI
ROI looks implausibly high	Revenue used as the return	Use gross profit, then subtract total costs
Platform ROAS differs from your shop's numbers	Attribution window, model or double counting	Compare against the shop's own sales and agree one source
ROAS falls when the budget rises	Diminishing returns as spend reaches less-interested audiences	Raise budgets in steps and watch ROAS against break-even
ROI swings wildly month to month	Small numbers or one-off costs	Report over longer periods; separate one-off costs

Frequently asked questions

What is the difference between ROI and ROAS?

ROAS divides revenue from ads by ad spend. ROI divides profit by the total investment. ROAS measures ad efficiency; ROI measures whether the whole activity made money.

Is a higher ROAS always better?

Not on its own. In the worked example, the campaign with the higher ROAS made less profit because it sold lower-margin products and had higher fees.

What is a good ROAS?

It depends on your margin. Anything above your break-even ROAS (1 ÷ gross margin) covers product costs and ad spend; your target should also cover other costs and leave a profit.

How do I calculate break-even ROAS?

Divide 1 by your gross margin as a decimal. With a 40% margin, break-even ROAS is 1 ÷ 0.40 = 2.5.

Can ROI be negative while ROAS is positive?

Yes. ROAS is positive whenever ads bring any revenue. ROI turns negative when profit does not cover all the costs.

Should ROI use revenue or profit?

Profit. Using revenue ignores the cost of what you sold and makes results look far better than they are.

Is ROAS a percentage or a ratio?

Both forms are common: a ROAS of 4 can be written as 4:1, 4x or 400%. Pick one form and use it consistently in reports.

Which metric should I report to management?

ROI for decisions about budgets and channels, because it reflects profit. Include ROAS as a supporting metric for how efficiently the ads themselves perform.

Does ROAS apply to SEO or email?

Not directly, because those channels have no ad spend. Use ROI, counting tools, content and staff time as the investment.

Why does Google Ads call conversion value / cost an ROI estimate?

Its help article describes the column that way, but the calculation uses conversion value and ad cost only, which matches ROAS as defined here. Treat it as ROAS unless your conversion values are profits.

Next step

Work out your gross margin with the profit margin calculator, turn it into a break-even ROAS, and compare it with last month's campaign ROAS. Then calculate full ROI for your biggest campaign with the ROI calculator, using profit as the return.