To estimate the ROI of your Google Ads and Meta Ads campaigns before spending, you need three numbers: the average CPC in your sector, the conversion rate of your landing page, and the average value of a customer. A free simulator combines them to project the clicks, conversions and ROAS you can expect from the budget you have in mind.
63% of businesses that invest in online advertising do not measure their return properly. They launch campaigns on a budget set by instinct, then find out too late that every euro spent was not bringing in enough customers to pay for itself.
This guide gives you the benchmark numbers by sector and the method to work out your own profitability in 5 minutes, before you spend a single euro.
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How do average CPC and conversion rate decide whether a campaign pays off?
Average CPC and conversion rate are the two numbers that decide whether an advertising campaign pays off, because together they set your cost per acquisition (CPA). If your average CPC is 2€ and your conversion rate is 4%, every customer costs you 50€ to acquire through advertising. If a customer is worth 200€ on average, you are profitable. If not, you lose money on every click.
Average CPC in France varies widely by sector:
Benchmark conversion rates:
The formula: ROI = ((Revenue generated - Budget) / Budget) × 100. With 1 000€ invested, a 2€ CPC, a 4% conversion rate and 150€ per customer: 500 clicks → 20 customers → 3 000€ of revenue → 200% ROI.
That simple formula turns advertising from a gamble into arithmetic. Before you launch anything, ask yourself one question: if my campaign performs at my sector average, do I make money? If the answer is no even in the average scenario, fix your offer or your page before investing.
How does a free advertising ROI simulator work?
A free advertising ROI simulator works by combining your budget, the average CPC in your sector and your conversion rate to project clicks, leads and expected ROAS. The result is a realistic estimate based on current market data, not on generic averages.
The 3 steps of the simulator:
Step 1: Choose your platform and your sector
Select Google Ads or Meta Ads, then your line of business. The tool automatically loads the current average CPC for your market.
Step 2: Set your budget and the value of a customer
Enter the monthly budget you have in mind and the average value of a customer for your business. You can adjust the conversion rate if you already know your own performance.
Step 3: Get your full simulation
The tool projects estimated clicks, expected conversions, cost per acquisition (CPA) and ROAS. You know whether your campaign will be profitable before spending anything.
What is the difference between Google Ads and Meta Ads in ROI terms for a small business?
For a small business, Google Ads usually delivers better ROI on services with high purchase intent (trades, doctors, solicitors), while Meta Ads performs better for building awareness or selling products bought on impulse. The key difference: Google Ads captures existing demand, Meta Ads creates demand.
| Criterion | Google Ads | Meta Ads |
|---|---|---|
| Purchase intent | High (active search) | Low (interruption) |
| Average CPC | Higher | Lower |
| Conversion rate | 3-5% | 1-3% |
| Best for | Local services, B2B | E-commerce, awareness |
| Recommended minimum budget | 500-1000€/month | 300-500€/month |
| Time before results | 2-4 weeks | 4-8 weeks |
For a small business, the ideal is often to run both: Google Ads to capture immediate demand, Meta Ads to build awareness and retarget visitors who did not convert.
The 4 mistakes that destroy an advertising campaign's ROI
1. Sending clicks to the homepage
A homepage is not a landing page. It presents everything and converts very little. Every campaign needs a dedicated page with one offer, one call to action and no distractions (simplified menu, no outbound links).
2. Running without conversion tracking
If you do not know how many calls or form submissions come from your ads, you are flying blind. Set up Google Ads conversion tracking, or install the Meta Pixel with the "Contact" event, before you spend anything.
3. Launching on too small a budget
Below 300€/month on Google Ads, the machine learning algorithms do not get enough data to optimise. The result: higher CPC, fewer conversions. 600€/month for 2 months beats 100€/month for a year.
4. Targeting far too broadly
"The whole of France" for a local tradesperson. "18-65" with no interest criteria. That kind of targeting spreads your budget across audiences who will never buy. Always start with tight geographic targeting (your town plus 20 km) and exact match keywords.
Frequently asked questions about advertising ROI
Are the simulator's estimates reliable?
The estimates are built on up-to-date average CPC data by sector and benchmark conversion rates from industry sources (Google, WordStream, HubSpot). They are a realistic projection, not a guarantee. Real performance varies with the quality of your ads, your landing page and your targeting, so two campaigns with the same budget can deliver very different ROI.
What is the minimum budget for a profitable Google Ads campaign?
Google imposes no technical minimum, but below 500€/month the machine learning algorithms do not get enough data to optimise your campaigns properly. We recommend a minimum of 500 to 1 000€/month to get meaningful, comparable results on Google Ads. On Meta Ads, 300 to 500€/month is enough to start with usable data.
Is a positive ROI possible in the first month?
Yes, it is possible on Google Ads Search if your sector is not too competitive, your landing page is well optimised and your offer is clear. In practice the first month is often a learning phase where cost per acquisition is higher than it will be later. Profitability usually improves from the second or third month, as Google optimises bidding towards the segments that convert best.
Which numbers should you watch first in your advertising dashboard?
Three metrics are enough to run a small business campaign: your real CPC (cost per click), your conversion rate (clicks to leads) and your cost per acquisition. If your CPA is higher than the value of a customer, the campaign is losing money. Ignore CTR on its own: a high click rate with a low conversion rate means your ads are attracting unqualified traffic rather than potential buyers.
How can a tradesperson make Google Ads pay off on a small budget?
A tradesperson can make Google Ads pay off on 300 to 500€/month by targeting only high purchase intent keywords ("emergency plumber town]", "electrician quote [town]"), limiting delivery to a 20 km radius and building a dedicated page with a click-to-call number. At ConvertiLab, an electrician in the Paris region generated 8 quote requests in 2 weeks on 400€ of spend, a cost per lead of 50€ for jobs worth at least 1490€. The ROI was positive in the first week of delivery. [Simulate your campaign profitability for free →
