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Google Ads CPC and ROAS calculator

Work out what your budget actually buys: clicks, leads, customers, cost per acquisition and return on ad spend.

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Get a proper audit

Monthly ad budget (AUD)

Average cost per click (AUD)

Landing page conversion rate (%)

Clicks that become an enquiry. Three to five per cent is typical for a service business.

Lead to customer rate (%)

Enquiries your sales process actually closes.

Average customer value (AUD)

Gross margin (%)

What that budget buys

0Clicks

0Enquiries

0Customers

$0Cost per enquiry

$0Cost per customer

$0Revenue

The number that decides it

0xReturn on ad spend

$0Gross profit after ad spend

The thinking behind it

Work Backwards From What a Customer Is Worth

Most Google Ads conversations start with a budget and a hope. We would rather start at the other end.

Say a customer is worth $2,400 to you at a 45 per cent margin. That means you can spend up to $1,080 winning one before the campaign starts costing you money. Every other number on this page hangs off that ceiling. Clicks, enquiries, the lot.

The two inputs people guess worst are conversion rate and close rate. Conversion rate is the share of clicks that turn into an enquiry; for a Perth service business with a decent landing page, three to five per cent is realistic. Close rate is what happens after the phone rings. It is usually the number with the most slack in it, and the one nobody wants to talk about.

Here is the uncomfortable bit. When a campaign is not working, the instinct is to throw more money at it. Run it through the calculator and you will usually see the opposite: at a poor conversion rate, a bigger budget just buys more expensive failure. Lift the landing page from two per cent to four and you halve your cost per customer without touching ad spend at all.

Worked examples

Three Perth Businesses, Run Through the Numbers

Illustrative figures, not client data, but the kind of numbers we see across the metro area. One works, one works if you are honest about it, and one quietly bleeds money every month.

Emergency plumberJoondalup

Spending $2,500 a month on Google Ads

+$1,833a month after ad spend

Clicks cost $9 each, which sounds painful. But someone searching “blocked drain Joondalup” at 7pm wants a plumber now, not a quote for next week. High intent carries the cost.

$188per customer

3.5xROAS

$325break-even

How we got there

278 clicks at $9.00. 8% call or enquire, 60% of those book in, at $650 a job and a 50% margin.

Physio clinicSubiaco

Spending $1,500 a month on Google Ads

+$5,233a month after ad spend

Looks brilliant, and mostly is. The catch: $570 a patient assumes six sessions at $95. If most people only come back once, this picture changes quickly. Lifetime value is fine. Wishful lifetime value is not.

$76per patient

7.5xROAS

$342break-even

How we got there

469 clicks at $3.20. 6% book online or call, 70% turn up, worth $570 each at a 60% margin.

Homewares storeOsborne Park

Spending $4,000 a month on Google Ads

−$793a month after ad spend

The one that stings. A 2.3x ROAS looks respectable on a dashboard, but at a 35% margin every month costs more than it earns. Lift the store’s conversion rate to 2.6% and the same spend makes $633 instead.

$61per order

2.3xROAS

$49break-even

How we got there

3,636 clicks at $1.10. 1.8% buy, at a $140 average order and a 35% margin.

The pattern? Click price matters far less than people think. The plumber pays eight times more per click than the online store, yet makes money every month while the store loses it. Margin, conversion rate and close rate decide whether Google Ads works for you. The click price just decides how quickly you find out.

CPC Calculator, Answered

The questions business owners ask us once they have played with the numbers. Still stuck? Call 1800 967 911 and talk it through with someone in our Wanneroo office.

Get your account reviewed

What is a good return on ad spend?

It depends entirely on your margin. At 40 per cent gross margin you need roughly 2.5x just to break even, so a 3x ROAS is thin. At 80 per cent margin, 2x is comfortably profitable. Anyone quoting a universal target ROAS without asking about your margin is guessing.

What does a click cost in Perth?

Anywhere from well under a dollar for some retail searches to $10 or more for emergency trades and legal work. Set Keyword Planner to Perth or Western Australia rather than all of Australia; Sydney and Melbourne auctions can skew the national figures upwards.

What conversion rate should I use?

Your own, if GA4 is tracking enquiries properly. If not, three to five per cent is a fair planning figure for a service business with a decent landing page. Ecommerce usually runs lower, often one to three per cent. When in doubt, model the pessimistic case and treat anything better as upside.

Why is my actual cost per click higher than the estimate?

Keyword Planner gives ranges, and the auction moves daily. Broad match, low quality scores and competitors bidding on your brand name all push the real figure up. The gap between forecast and actual is one of the first things we check when an account underperforms.

Should I include GST in these numbers?

Pick one and stick to it. If your customer value is ex GST, keep the budget ex GST too. Mixing them throws the margin out by about ten per cent, which is plenty to make a losing campaign look like a winner on paper.

How long should I test before trusting the numbers?

Give it four to eight weeks and at least a few hundred clicks. Week one is noisy; Google is still learning, and one big job or one quiet week can swing everything. Judge the trend, not the Tuesday.

Does this account for the sales cycle?

No. It is a steady-state monthly model. If your sales cycle runs three months, the customers from this month’s spend arrive later, so early months will look worse than the calculator suggests. Longer cycles need a cash flow view alongside this.

What about lifetime value rather than a single sale?

If customers genuinely come back, use lifetime value and the maths still holds. Be honest about it, though. Inflating lifetime value to justify a cost per customer your cash flow cannot carry is the most common way bad accounts get made to look good.

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