Ad budgets: how much to spend without going broke
Photo: Avila Ops Tecnologia
An ad budget that will not break the business comes from two calculations: how much remains from each sale after its costs, and how much a sale generated by advertising costs, measured in your previous campaigns. If each sale leaves R$ 40 in margin and each ad-generated sale costs R$ 15, below the ceiling of half the margin, the ad pays for itself, and the budget can increase while that relationship holds. If it costs R$ 50, the ad is buying losses, and a larger budget means larger losses.
If you have never measured this, you do not have the second calculation. Run a small ad in October with the pixel installed, and enter November knowing how much a sale costs. Guessing your Black Friday budget is the fastest way to spend R$ 3,000 to sell R$ 2,000.
How do you calculate how much you can spend?
Photo: Avila Ops Tecnologia
First, margin per sale: average order price minus product cost, payment fee, tax, shipping you cover, packaging, and each order’s share of the store’s fixed costs, such as platform fees, rent, and salaries, divided by monthly orders. This is what remains to pay for advertising and still make a profit. Second, how much of that margin you are willing to spend on advertising: half is a reasonable limit for anyone seeking a profit on the first purchase; spending more only makes sense with measured repeat purchases.
Third, the cost per sale shown by the pixel: total campaign spend divided by the number of recorded purchases. Check that each purchase recorded by the pixel corresponds to a paid store order, using the order number: the pixel can overcount or undercount. Do not compare it with all orders during the period because organic sales, email sales, and repeat purchases are included there too. With these three numbers:
| Number | How to get it | Example |
|---|---|---|
| Margin per order | Average price minus all costs | R$ 40 |
| Ceiling per sale | Half the margin | R$ 20 |
| Measured cost per sale | Campaign spend divided by purchases | R$ 15 |
| Decision | Cost below ceiling: you can increase | Yes, carefully |
If cost per sale is below the ceiling, the budget can increase gradually, 20% every two or three days, while checking whether cost per sale holds steady. It usually rises as the budget grows because the ad reaches less interested people. The point where cost per sale reaches the ceiling is your maximum budget.
How do you test in October with little money?
Spend R$ 15 to R$ 30 per day for 10 to 14 days on an ad for one campaign product, with the pixel recording purchases. The guide to setting up the pixel and measuring conversions is a prerequisite; without it, you will have clicks without knowing what they became.
At the end of the test, you have cost per click, the number of clicks that became purchases, and cost per sale. Use that to build your November budget.
If you sell through WhatsApp rather than the store, measure cost per conversation started and the rate at which conversations become sales, recorded in CRM. The guide to Meta Ads for generating WhatsApp contacts shows how.
What should you do with the budget during the campaign?
Divide it into three parts: people who have already visited or purchased, the audience with the lowest cost per sale, as explained in the remarketing guide, receive as much as that audience can absorb without showing the same people the ad too often; a portion goes to new audiences similar to past buyers; and a small portion goes to testing creative. Remember that Meta’s daily budget is an average: on a given day, it can spend up to 75% more. For a firm overall cap, use a lifetime campaign budget or an account spending limit; neither caps spending on an individual day, so monitor cost per sale daily during the peak.
An accessories store spends R$ 20 per day in October for 12 days: it spends R$ 240, makes 11 sales, and has a cost per sale of R$ 22. Its margin per order is R$ 55, and the ceiling is R$ 27. In November, it starts at R$ 60 per day and raises that 20% at a time (R$ 72, then R$ 86) while cost per sale stays around R$ 24, stopping increases when it reaches R$ 27.
What to do now
Calculate margin per order and the ceiling per sale today. Install the pixel and run the R$ 15 to R$ 30 daily test in October. If you want advertising measured end to end, from click to CRM, with a budget based on calculations rather than guesswork: avilaops.com/meta-ads-para-empresas or contact us on WhatsApp: wa.me/5517997811471.
Frequently asked questions
How much should a small business spend on advertising per month?
Whatever the margin from ad-generated sales can cover. There is no right amount without measurement: start at R$ 15 to R$ 30 per day, measure cost per sale, and increase while it remains below your ceiling.
Are Black Friday ads more expensive?
They usually are. Competition for attention increases, and cost per click rises. That is why the less expensive audience of past visitors should receive as much of the budget as it can absorb, and why you need to set the ceiling per sale beforehand.
What should you do if the ad does not sell?
Pause before spending the budget and examine the funnel: cheap clicks with no purchases point to the page or price; expensive clicks point to the creative or audience. Do not increase the budget to “give it time” to work.
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