The sum that decides it
You need two numbers from your own business:
- Profit per sale. What a typical job or order leaves you after materials and labour, not the invoice total.
- Close rate. Out of every ten genuine enquiries, how many become paying customers.
The most you can pay for an enquiry and break even = profit per sale × close rate.
As an illustration: if a job leaves you $600 and you win one in three enquiries, you can pay up to $200 per enquiry before Google Ads stops making money. If a job leaves you $90 and you win one in five, the ceiling is $18, and most competitive searches will cost more than that.
When Google Ads tends to work
- People search for what you sell, in words you can predict, when they are ready to buy.
- Each sale is worth enough to leave room under the ceiling above.
- Someone answers the phone and replies to enquiries quickly. Ads create enquiries; they do not close them.
- You can track which enquiries came from ads, so you can see the real cost per customer.
Our guide on whether SEO is worth it for a small business runs the same test for organic search.
How to test it without risking much
- Work out your break-even cost per enquiry with the sum above.
- Set up conversion tracking for calls and forms before the first ad runs.
- Start with your most profitable service, in the area you serve best, with a budget you are comfortable losing while you learn.
- Judge it on cost per enquiry and cost per customer, not on clicks or impressions.
Remember that Google adds 10% GST to ad spend for Australian accounts, so build that into the budget. For typical click prices and monthly budgets, read what Google Ads costs in Australia, and for the trade-off with organic search, SEO vs Google Ads for leads.
Sources
- Google Ads Help: taxes in Australia (opens in a new tab), checked 5 Oct 2026
How this article was made: Alex Yeldizian researched it and checked every claim against the sources below, with AI helping to organise and summarise the notes. Reviewed on 27 October 2026.
