How much should a small business spend on ads? A testing-budget method

“How much should we spend on ads?” usually gets answered with a percentage of revenue or whatever a competitor spends. Neither tells you whether a campaign can actually work. A budget should come from two things: what you can afford to pay per sale and how much data the platform needs to learn.

Step 1: your target cost per sale

Spending 100% of gross profit on the first sale is break-even. Go higher only if you know customers come back. Use your own repeat-purchase data, not hope.

For businesses that sell through enquiries

Convert cost per sale into cost per lead with your close rate:

• Close rate 20% → target cost per lead = AED 90 × 20% = AED 18

Measure close rate from your CRM, by lead source if you can. Leads from ads often close at a different rate from referrals.

Step 2: the volume the platform needs

Automated bidding learns from results. Two anchors from the platforms’ own documentation:

• Meta: ad sets usually exit the learning phase after about 50 results in the week after the last significant edit.
• Google: to judge Smart Bidding, look at periods with at least 30 conversions (50 for Target ROAS), such as a month or longer.

Step 3: multiply

Weekly budget for one Meta ad set ≈ target cost per result × 50.

These are worked examples from the inputs above, not benchmarks. Your costs depend on your market, offer and creative.

The second row shows the problem many small stores hit: optimising directly for purchases needs a budget they don’t have.

Step 4: if the number is bigger than your budget

You have honest options, not tricks:

1. Run fewer ad sets. One well-funded ad set learns. Five underfunded ones don’t. Meta’s guidance is to combine similar ad sets so learning is combined.
2. Optimise for a more frequent step such as add to cart or initiated checkout, while purchase volume builds. Watch that cost per actual sale still works.
3. Use Google Search first if people search for what you sell. You pay for clicks from people already looking, and you can start with fewer conversions.
4. Accept “Learning limited” and judge results over a longer period. Results will be less stable.
5. Raise the value of a sale: bundles, higher-value services, or a better follow-up process. A higher target cost per result lowers the volume problem.

Step 5: set a test budget and a stop rule

A test budget is the amount you’re prepared to spend to learn whether a channel works:

• Test budget = weekly learning budget × number of weeks (usually 4–8)
• Stop rule: if cost per sale stays above break-even after the test budget, with tracking and follow-up checked, stop or change the offer.

Write both down before the first campaign goes live.

Frequently asked questions

Isn’t a percentage of revenue simpler?

It’s a sensible ceiling for total marketing spend. It doesn’t tell you whether a campaign can learn, which is what the method above does.

What about Google Ads budgets?

Google treats your daily budget as an average: a campaign can spend up to twice it on a busy day, but over a month you won’t be charged more than 30.4 times the daily average. Plan around the monthly figure, and use the same target cost per conversion.

Can we start smaller to test?

Yes, if you accept that results will be noisier and the platform won’t fully optimise. Use the small test to check tracking, landing page and follow-up, which you need anyway.

The calculator does all of this with your own numbers. If you’d like help planning the test and setting up tracking, that’s part of our traffic sources service.