ROAS is revenue divided by ad cost, and nothing else
Return on ad spend (ROAS) is the revenue an ad campaign generates divided by what you paid for the ads. Spend $1,000 and book $5,000 in tracked sales, and your ROAS is 5, which people write as 5x, 5:1 or 500%.
The formula is simple on purpose, and that is also the problem. Revenue is the numerator, so ROAS knows nothing about what the product cost you, what shipping and returns took back, or whether the customer would have bought anyway. Google Ads and Meta both report it as a headline number, and both are measuring revenue, not profit.
Is a 4x ROAS good? It depends on one number you already have
A 4x ROAS is good if your margin after product cost is above 25 percent, and a loss if it is below. The number you need is your break-even ROAS, which is 1 divided by your margin. At that point every dollar of ad spend returns exactly the gross profit it consumed.
Here is the arithmetic for a range of margins. It is just 1 divided by the margin, so there is no benchmark or survey behind it.
| Gross margin on the order | Break-even ROAS | What a 4x ROAS does |
|---|---|---|
| 20% | 5.0x | Loses money on every sale |
| 25% | 4.0x | Exactly break-even |
| 33% | 3.0x | Profitable, with a thin cushion |
| 40% | 2.5x | Comfortably profitable |
| 50% | 2.0x | Room to spend more |
This is why asking what a good ROAS is gets you an unhelpful answer from any agency or article that quotes one number for every business. A store selling at a 50 percent margin should be unhappy with a 2x. A store at 20 percent needs 5x just to stand still.
How a 4x ROAS can still lose money
Take a $100 order at a 30 percent gross margin, so $30 of gross profit before advertising. At a 4x ROAS the ads cost $25 for that order, leaving $5. At 3x the ads cost about $33, and you are $3 under water on every sale while the dashboard shows green.
That example is generous, because gross margin is not what you keep. Payment fees, fulfilment, returns and discount codes all come out of the same $30. If a meaningful share of orders come back, the revenue the platform counted was never really yours. I always ask for the margin figure after returns and fees, because a break-even ROAS built on the wrong margin is wrong in the direction that hurts.
If you want the customer-level version of this question, my breakdown of customer acquisition cost against lifetime value shows how repeat purchases change what you can afford to pay on the first order.
Brand search makes the blended number lie
Blended ROAS mixes campaigns that find new customers with campaigns that collect people who were already coming to you. The second group looks wonderful and adds little.
In the accounts I run, brand terms commonly take 20 to 35 percent of clicks while reporting a ROAS several times higher than everything else. Fold that into one account-level figure and a 6x blend can sit on top of a non-brand campaign that is barely breaking even. Performance Max does the same thing when brand and existing customers are not excluded or reported separately.
So I split the reporting before I touch bids: brand, non-brand search, Shopping and Performance Max each get their own ROAS next to their own break-even. If you are planning spend from the top, the logic in planning a marketing budget backwards from the sales you need applies here too, because it starts from the same margin arithmetic.
What to check before you trust a ROAS report
Before I act on any ROAS figure I check four things, in this order. Each one can change the answer by more than any bid adjustment will.
- What counts as revenue. Some accounts import order totals including tax and shipping, which inflates ROAS against a margin calculated on the product price alone.
- The attribution window. A longer window credits ads with sales that would have happened anyway, and a shorter one hides slow buyers. Compare the same window across campaigns or the comparison is meaningless.
- Duplicate conversions. A purchase tag firing twice, or an imported GA4 event on top of a native Google Ads tag, produces a ROAS that looks excellent and is simply wrong.
- New versus returning customers. A campaign that mostly re-sells to existing buyers can show a strong ROAS and add almost no growth. If the platform lets you report new-customer value separately, do it.
None of this requires a data team. It needs one afternoon with the conversion actions list, the order export from your store, and the willingness to accept that the first number you were shown was flattering.
ROAS and ACoS are the same maths upside down
Amazon sellers see ACoS, the advertising cost of sales, which is ad spend divided by ad sales. ROAS is its reciprocal, so a 25 percent ACoS equals a 4x ROAS and a 20 percent ACoS equals 5x. That also answers the search that sends many people here: if your ACoS is 25 percent and your margin is 30 percent, you are making a small profit, and if your margin is 20 percent you are not.
Setting a target ROAS in Google Ads without strangling the campaign
Target ROAS is a Smart Bidding strategy in Google Ads that tries to hit the return you set, using the conversion value you report. Two things decide whether it works: the conversion values have to be accurate, and the target has to be one the campaign has actually achieved in the past.
My approach is to take the break-even ROAS for a product group, add the margin of safety I want, and then compare it with what the campaign did over the last few weeks. If the target is far above recent results, volume collapses because the system stops bidding on auctions it cannot be sure of. Move the target in small steps, and give each step enough conversions to read. Google's own documentation on Smart Bidding in the Google Ads Help Center explains the mechanics and the data it needs.
If your store sells products with very different margins, feed margin or profit into the platform as conversion value instead of raw revenue. Then a 3x ROAS on a high-margin product and a 3x on a low-margin one stop looking identical to the bidding system. My guide to PPC ROI metrics and attribution covers how to make that tracking trustworthy.
When ROAS is the wrong metric
ROAS works when a click turns into a priced order inside one session. It breaks down for lead generation, long sales cycles and anything where revenue arrives weeks later through a sales team. A plumber, a law firm or a B2B software company should be tracking cost per qualified lead and cost per booked job, with revenue fed back when it is known.
It also tells you little about cross-channel journeys. A Meta ad that starts the purchase and a Google brand search that finishes it will each claim the sale. For that, read cross-channel attribution for Google Ads, Meta Ads and organic, and treat any single platform's ROAS as one witness rather than the verdict.
If you run an online store and want someone to rebuild this chain from tracking to margin to target, that is the core of my ecommerce PPC work.
