Check margins, conversion rates, click costs, tracking and budget before buying traffic. A dog harness example shows how to judge the numbers.

Paid search can put a new store in front of people already looking for its products. But a sale in the dashboard doesn’t prove the channel is paying its way. Before spending, a founder needs to know what each order earns, whether the store can convert unfamiliar visitors, and how much the learning period will cost.
That’s the case for treating Google Ads as a measured experiment, not a launch-day checkbox. The five-part test below uses a hypothetical dog harness store to make the calculations concrete. The underlying checklist draws on audits of more than 1,300 online stores and is designed to help founders spot weak economics before ad costs add pressure.
Start with the figures your own business can support: supplier invoices, shipping charges, payment fees, store visits and orders. The example numbers illustrate the method; your results will depend on your product, market and site.
First, calculate what an order can contribute
A store can report $75 in sales from a harness and still have far less than $75 available to acquire the customer. The supplier, delivery, packing and payment costs all come out first. The amount left after those order-level costs is the contribution margin.
For the example store, one order works out this way:
- $75 average order value
- $22 for the harness, including freight to the store
- $8 to ship and package it for the customer
- $2.25 in payment processing fees, estimated at about 3%
- $2.75 reserved for returns and exchanges
- $40 contribution margin per order
That $40 is the ceiling for what the store can spend to acquire an order while covering the listed variable costs. Spending $41 leaves the store a dollar short on that sale, even if the advertising dashboard shows revenue. The calculation helps explain how a business can see revenue rise while cash in the bank falls; the source article discusses that problem in more detail here.
Use actual supplier and delivery costs rather than estimates lifted from a competitor. Include costs that rise with each order, such as packaging, payment processing and a realistic allowance for returns. Leave fixed costs such as rent, software and the founder’s salary out of this particular calculation: they generally don’t change with one additional sale.
Don’t rely on future repeat purchases to make a first order look profitable if the store doesn’t yet have dependable evidence that customers return. A six-week-old shop may eventually build repeat business, but it can’t safely assume a pattern it hasn’t observed. For the readiness test, make the first order carry its own variable costs.
Pass this part when your contribution margin is built from your own costs. If you can’t show where the number came from, the rest of the advertising math will be unreliable.
Next, make sure the store already converts visitors
Paid traffic brings people to the store; it doesn’t repair a product page that fails to persuade them. If visitors arriving through social media or unpaid search aren’t buying, paying for more visits can make the same weakness more expensive.
Conversion rate is the share of visits that result in an order. Shopify displays it in the Analytics dashboard. The article’s guidance is to set aside launch-week activity, when friends and family may account for many of the orders, and wait until the store has at least 500 visits before putting much weight on its rate.
A rate below 1% is a reason to pause and investigate. The product page may not explain the offer clearly, the price may not fit what shoppers expect, or shipping charges shown at checkout may be putting people off. Each is a store issue to examine before adding paid visits.
In the harness example, the store has recorded 1,600 visits since launch week and 40 orders. Forty orders divided by 1,600 visits equals a 2.5% conversion rate, which clears the article’s suggested threshold.
That figure is a starting point, not a promise that paid visitors will behave the same way. Its value is that the store has some evidence that people beyond its launch circle will buy. As paid traffic arrives, the founder can compare actual results with the assumptions used to plan the spend.
Compare click costs with the margin
Once you know both the contribution margin and the store’s conversion rate, estimate what it might cost to acquire an order through search. Google’s Keyword Planner provides estimated bid ranges for searches. Enter phrases a prospective customer might use, such as “no pull dog harness,” then choose a representative click-cost estimate from the range.
To turn a click estimate into a rough cost per sale, divide the cost of one click by the conversion rate expressed as a decimal. At an 85-cent click price and a 2.5% conversion rate, the estimate is $0.85 divided by 0.025, or $34 per order. That calculation assumes the paid visitors convert at the same rate as the store’s existing visitors, so treat it as a planning estimate and replace it with observed results as they come in.
The harness store’s $40 contribution margin would leave about $6 after a $34 advertising cost. That is a narrow cushion, and it doesn’t mean every order will produce the same outcome. It does show that the estimated click price could fit within the margin if the conversion assumption holds.
Change just one assumption and the answer shifts. At $1.40 per click and the same 2.5% conversion rate, acquiring an order would cost about $56. Against a $40 contribution margin, that sale would be $16 short before fixed costs.
These estimates help founders decide whether to test a keyword, revisit the store’s economics or wait. They also give the team a concrete reference point for evaluating later results, instead of relying on whether the sales figure looks encouraging.
Know your break-even return
Google Ads reports return on ad spend, or ROAS: sales revenue attributed to advertising divided by ad spend. Because ROAS uses revenue rather than the amount left after variable costs, it needs to be read alongside contribution margin.
The break-even ROAS in this framework is average order value divided by contribution margin. For the harness store, $75 divided by $40 equals 1.875, or about 1.9. A campaign needs to return roughly $1.90 in sales for every $1 spent on advertising to cover the order’s variable costs under these assumptions.
A ROAS near 1.9 can sound like nearly twice the money back. But the store still has to pay for the harness, shipping, processing and returns allowance. That’s why revenue alone can make a weak result look better than it is. Compare the reported ROAS with your own break-even calculation, and update the calculation if your observed costs or order values differ.
The estimate also depends on which sales Google attributes to ads. That makes the next readiness question practical as well as technical: can the store verify that a purchase happened and that its value was recorded correctly?
Check that purchases are being tracked
Automated bidding uses purchase data it can see. If tracking is missing or misconfigured, the system has a poor signal to learn from, and the store owner has a poor basis for judging results.
Purchase conversion tracking connects an order and its value to an advertising interaction. Shopify’s Google & YouTube app can help set up purchase tracking. Before spending, confirm that Google Ads marks the purchase conversion as active and records the actual order value rather than assigning every purchase a flat $1.
After ads have run, compare a month of purchases reported in Google Ads with the store’s order records. If the advertising account claims more purchases than the store received, review the setup and reporting settings. Purchases could be counted more than once, or the two systems could be using different settings.
This check matters because a polished report can still be built on incorrect inputs. If the recorded sale count or value is wrong, ROAS can give the team a misleading view of what its spend accomplished. A short check before launch can prevent days or weeks of interpreting numbers that don’t describe the store’s orders.
Set aside enough budget to learn
The first stretch of advertising is a paid experiment. It needs enough sales to provide useful evidence, and a budget the business can afford to put at risk while gathering that evidence.
The article’s working benchmark is about 30 sales before judging profitability or setting a profit target for Google. With fewer orders, a small run of unusually good results can make a weak campaign seem stronger than it is. Thirty is a practical threshold offered here, not a guarantee that every store will have a definitive answer at that point.
Work backward from the target. At a 2.5% conversion rate, 1,200 clicks would be needed to produce 30 orders on average. At 85 cents per click, that works out to $1,020 in ad spend. Spread across three months, the example store would need about $340 a month.
The budget also needs to be money the business can spare. If losing $1,020 would put an inventory order or payroll at risk, the store should wait, even if its margins, conversion rate and click-cost estimates look promising. A learning budget should give the business room to evaluate results, not force it into a cash crunch.
Use the five answers to decide whether to start
The test covers five questions:
- Can you calculate contribution margin from your actual order costs?
- Does the store already convert visitors who aren’t just friends and family?
- Do estimated click costs fit within what an order contributes?
- Can Google Ads record purchases and their real values?
- Can the business fund the learning period without putting essential spending at risk?
Passing all five supports a measured test. Failing the tracking or budget question means the store needs to address that readiness gap first. Tracking may be possible to set up in a few days; a workable budget takes planning and money set aside.
Failing on margin, conversion or click economics points to a problem in the store’s underlying numbers. A weak margin, a site that isn’t converting or a click price above what a sale can support are reasons to wait. Advertising would add cost before the business has dealt with the constraint.
Depending on what the figures show, work on pricing, the product page or average order value, then run the calculations again. The purpose of the test is to make the bottleneck visible while it’s still possible to address it without paying for traffic.
Give the first 90 days a clear structure
Once the store passes, a defined schedule can keep early decisions tied to evidence. The recommended approach begins with a simple Google Ads setup for beginners, then adds changes as the store gathers results.
Days 1 to 30: keep the setup focused
Start with one Search campaign built around the best-selling product. Use exact match keywords for product names customers search for. Switch off the Display Network and Search Partners so the clicks come from Google Search itself.
Set bidding to maximize conversion value without a target, use the daily budget calculated from the learning plan, and avoid unnecessary changes during the first two weeks. A stable initial setup gives the store a clearer view of how its assumptions are holding up.
Days 31 to 60: review the searches
Each week, check the search terms report to see which searches triggered the ads. Mark irrelevant terms as negative keywords so the store can stop paying for them. In the harness example, “how to make a dog harness” is a poor match for a shop selling finished products.
Pause a keyword if it has spent twice the break-even cost per sale without producing an order. For the harness store, twice its $40 contribution margin is $80. This gives the team a specific review point while it learns, rather than leaving every keyword running without scrutiny.
Days 61 to 90: compare results with the economics
By this stage, the store should be approaching 30 sales if the original click and conversion estimates hold. Divide sales revenue attributed to ads by ad spend to calculate actual ROAS, then compare that result with the break-even figure established earlier.
Check the store’s results across channels, too. Total sales divided by total advertising spend across every channel is known as the marketing efficiency ratio, or MER. It provides a broader view of marketing performance that doesn’t depend entirely on Google’s attribution.
If ROAS sits comfortably above break-even, the business can consider raising spend. One option is to set a target ROAS a little above break-even, which gives Google’s bidding a profitability goal. The platform asks for the target as a percentage: the harness store’s approximate 1.9 break-even ROAS becomes 190%. A 220% target would leave additional room if the store continues to perform as expected.
Increase the budget gradually, by about 20% at a time, while watching the results. If ROAS stays close to break-even, hold the budget and look for ways to improve the store’s economics. A clearer product page or a bundle that raises average order value may change the calculation more than a bidding adjustment.
If ROAS remains below break-even after 30 sales, stop spending and revisit the assumptions before committing more. Use the click prices and conversion rate the store actually achieved, then identify which part of the economics needs work. That keeps the next decision grounded in observed performance rather than the initial estimate.
The useful outcome of this test isn’t simply a yes or no. It’s a set of numbers the owner can use to decide what to fix, what to monitor and what the business can afford to learn. For the harness store, even a small gap between estimated acquisition cost and contribution margin calls for close attention as real results replace the model.
Image by DC Studio on Magnific
The source article appeared on StartupNation.