A lot of businesses approach advertising with one question:

“What ROAS should we aim for?”

It’s a useful metric, but it doesn’t tell you whether your advertising is actually making the business money.

A campaign can generate 4X ROAS and still be barely profitable, or even lose money.

The reason is simple: revenue is not profit.

To understand whether an advertising campaign can break even, you need to connect the entire chain:

Manufacturing → Variable Costs → Contribution Margin → Advertising → Fixed Costs → Profit

This article walks through that mathematics using a hypothetical U.S. furniture business selling sofas.

The numbers below are illustrative assumptions, not the actual economics of a specific furniture company. The purpose is to demonstrate how the model works.

1. Start With the Product, Not the Ad

Let’s assume the business sells a sofa for:

$1,500

That is our selling price.

But the business doesn’t keep $1,500.

The first question is:

How much does it actually cost to produce and deliver one sofa?

We start with COGS, or Cost of Goods Sold.

2. Calculate the Manufacturing Cost

Suppose the cost of producing one sofa looks like this:

Manufacturing Cost	Per Sofa
Wood / frame	$120
Foam / cushions	$100
Fabric / upholstery	$150
Springs / hardware	$50
Direct manufacturing labor	$100
Packaging	$30
Factory overhead allocation	$80
Inbound freight	$50
Total COGS	$680

Therefore:

COGS = $680

The business sells the sofa for $1,500.

So:

Gross Profit = Revenue − COGS 

$1,500−$680=$820

The business has $820 gross profit per sofa.

Its gross margin is:

820 / 1,500×100 = 54.67 % 

But we’re still not finished.

3. Gross Profit Isn’t the Same as Money Available for Advertising

This is where marketing calculations often go wrong.

Someone might look at the $820 gross profit and say:

“We have $820 gross profit, so we can spend up to $820 to acquire a customer.”

Not necessarily.

There can be additional variable costs associated with selling that sofa.

For example:

Variable Cost	Per Sofa
Delivery	$100
Payment processing	$45
Warranty / returns allowance	$30
Sales / installation / admin	$20
Total	$195

These costs aren’t necessarily part of manufacturing, but they occur because the sale happened.

So:

Contribution Before Advertising = Selling Price − COGS − Variable Costs

=1,500−680−195

= $625

Now we have one of the most important numbers in the entire advertising model:

$625 contribution per sofa before advertising

This is the amount available to pay for customer acquisition, fixed overhead, and ultimately profit.

4. Now Bring Advertising Into the Equation

Suppose the company spends:

$5,000/month on advertising

And generates:

20 sofa sales

Customer Acquisition Cost is:

CAC = Ad Spend / Customers

CAC = 5,000 / 20 = $250

The company is spending $250 to acquire each customer.

We already know that each sofa generates $625 before advertising.

Therefore:

Contribution After Advertising = $625 − $250 = $375

Each new customer contributes $375 toward fixed costs and profit after their advertising acquisition cost.

5. What Is the Break-Even CAC?

This gives us another useful formula.

If the business generates $625 contribution before advertising, the maximum CAC it can tolerate before the individual sale becomes contribution-negative is:

BreakEven CAC = Contribution Before Advertising

Therefore:

At a $625 CAC:

625 − 625 = 0

The sale generates no contribution after advertising.

At $700 CAC:

625 − 700 = -$75

The business is losing $75 on every newly acquired customer before even considering fixed overhead.

This is why your maximum CAC cannot be determined simply by looking at revenue or ROAS.

It comes from the economics of the product.

6. Now Add Fixed Costs

The business also has expenses that don’t change directly with every sofa sold.

For example:

Fixed Expense	Monthly
Warehouse / factory rent	$8,000
Salaried employees	$10,000
Management	$5,000
Software / insurance	$3,000
Utilities	$2,000
Other overhead	$2,000
Total Fixed Costs	$30,000

These costs exist whether the company sells 10 sofas or 100 sofas.

Now we can calculate the business-level break-even point.

7. Calculate Break-Even Sales

Our contribution before advertising is:

$625

Our CAC is:

$250

Therefore:

Contribution After Advertising = 625 – 250 =$375

The company needs to cover:

$30,000 monthly fixed costs.

Therefore:

BreakEven Units = Fixed Costs / Contribution After Advertising 

=30,000 / 375 = 80 sofas

So the business needs to sell approximately:

80 sofas per month

to break even under these assumptions.

8. What Does 80 Sofas Actually Mean?

Let’s verify the mathematics.

Revenue

80 × 1,500 = $120,000

COGS + other variable costs

We calculated total variable cost before advertising as:

$875/sofa

Therefore:

80 × 875 =$70,000

Advertising

At $250 CAC:

80 × 250 = $20,000 

Now:

120,000 − 70,000 − 20,000 = $30,000

And the company has:

$30,000 fixed costs.

Therefore:

30,000 − 30,000 = 0 

That’s the mathematical break-even point.

80 sofas → $120,000 revenue → $20,000 advertising → $30,000 fixed costs → $0 profit.

9. Now Connect Advertising to Sales

This is where the model becomes much more useful for a marketer.

We can work backwards from the number of customers we need.

Our simplified funnel is:

Sales = Impressions×CTR×CVR

Suppose we have:

$20,000 advertising budget

and assume:

$20 CPM

Then:

Impressions = 20×1,000

Impressions = 20,000

Now assume a:

1.5% CTR

Then:

1,000,000 × 1.5% = 15,000 clicks

Our CPC becomes:

20,000/15,000 = $1.33

Now we need those 15,000 clicks to produce our required 80 customers.

10. Calculate the Required Conversion Rate

We need:

80 customers

from:

15,000 clicks

Therefore:

Required CVR = 80 / 15,000

So the business needs approximately a 0.533% click-to-purchase conversion rate under these assumptions.

That’s a much more useful question than:

“Is $20,000 enough for advertising?”

The mathematical question becomes:

“Can our funnel turn 15,000 clicks into at least 80 customers?”

If yes, the economics work.

If no, we need to change something.

11. What Happens If Conversion Rate Changes?

This is where you can identify exactly where the problem is.

At 0.3% CVR

15,000×0.003 = 45 customers

Only 45 sofas.

The campaign won’t reach the required 80 sales.

At 0.533% CVR

Approximately:

15,000 × 0.00533 ≈ 80 

That’s approximately break-even.

At 1% CVR

15,000×0.01 = 150 customers

Now we’re dramatically above the required 80 sales.

Using our $375 contribution after advertising:

150 × 375 = $56,250 

Subtract $30,000 fixed costs:

56,250 − 30,000 = $26,250

So a better conversion rate can transform the economics without increasing advertising spend.

12. This Is Why ROAS Alone Can Be Misleading

Imagine someone tells you:

“We’re getting 4X ROAS!”

Sounds great.

Suppose:

Ad spend = $20,000

and:

Revenue = $80,000

Then:

ROAS = 80,000 / 20,000 = 4X

But the company doesn’t get to keep $80,000.

Suppose its contribution margin before advertising is only 30%.

Then:

80,000 × 30% = $24,000

Advertising cost:

$20,000\$20,000

Remaining:

24,000 − 20,000 = $4,000

And that’s before fixed overhead.

So a 4X ROAS doesn’t automatically mean a highly profitable campaign.

13. ROAS Has to Be Viewed Alongside Contribution Margin

Consider another company.

It gets only:

2.5X ROAS

It spends:

$20,000

and generates:

20,000×2.5=$50,000

But suppose its contribution margin before advertising is 60%.

50,000×60%=$30,000

After advertising:

30,000−20,000=$10,000

So the company with 2.5X ROAS could actually have better economics than the company with 4X ROAS.

The lesson isn’t that ROAS is useless.

It’s that:

ROAS must be interpreted alongside the business’s margins.

14. The Complete Profit Equation

We can now combine the entire model.

First:

Sales = Impressions × CTR × CVR

Then:

Revenue = Sales × Selling Price

Then:

Gross Profit = Revenue − COGS

Then:

Contribution Before Ads = Revenue − COGS − Other Variable Costs

Then:

Contribution After Ads = Contribution Before Ads − Ad Spend

And finally:

Net Profit = Contribution After Ads − Fixed Costs

Which can be condensed into:

Net Profit = (Sales × Contribution Before Ads) − Ad Spend − Fixed Costs

And because:

Sales = Impressions × CTR × CVR

we can go one step further:

Net Profit = (Impressions×CTR×CVR) × Contribution Before Ads − Ad Spend − Fixed Costs

That is the mathematical connection between advertising performance and business profitability.

15. What You Actually Need From a Business

If you’re building this model for a real furniture client, you shouldn’t simply make up a target ROAS.

You need their actual business economics.

Product information

Ask for:

• Average selling price
• Discounted selling price
• Average order value
• Manufacturing cost
• Raw material costs
• Direct labor
• Packaging
• Factory overhead
• Inbound freight

Selling and fulfillment costs

Ask for:

• Delivery cost
• Installation cost
• Payment processing fees
• Sales commissions
• Warranty costs
• Historical return rate
• Average return cost
• Damage/replacement costs

Fixed costs

Ask for monthly:

• Rent
• Salaries
• Management
• Utilities
• Insurance
• Software
• Warehouse costs
• Equipment
• Administrative expenses
• Other overhead

These numbers allow you to calculate the actual contribution margin and business break-even point.

16. Then Get the Company’s Historical Marketing Data

If available, ask for at least 6–12 months of:

• Ad spend
• Impressions
• CPM
• Clicks
• CTR
• CPC
• Leads
• Cost per lead
• Website conversion rate
• Purchases
• CAC
• Revenue
• ROAS

This is much more valuable than blindly assuming industry benchmarks.

If the company already has historical data, you can replace hypothetical CPM, CTR, CVR and CAC figures with its own observed performance.