To calculate ROAS, divide the revenue attributed to your ads by your ad spend — $75,000 in revenue on $10,000 of spend is a 7.5x ROAS. But that single division, read alone, is how profitable-looking campaigns lose money: it says nothing about your margin, your management costs, or what a customer is worth over time.
The full-funnel way is to carry one set of numbers all the way through — spend to lead to call to customer to lifetime value — so ROAS, CAC, and LTV all come from the same funnel and can't contradict each other. That's what this guide does, with one worked example throughout. Our free ROAS & CAC Calculator runs the identical math on your numbers, live.
What Are the Formulas?
Five divisions cover the whole funnel:
- ROAS = attributed revenue ÷ ad spend
- Cost per lead (CPL) = ad spend ÷ leads
- Media CAC = ad spend ÷ new customers
- Fully-loaded CAC = (ad spend + management fees + tooling) ÷ new customers — the honest one, because the platform bill was never your only cost
- Margin-adjusted LTV = customer lifetime revenue × gross margin — because you can't pay for ads with revenue you spent delivering the product
Two derived numbers do the judging: LTV:CAC (margin-adjusted LTV ÷ fully-loaded CAC, with 3:1 the common bar) and breakeven ROAS (1 ÷ gross margin — the multiple below which a campaign loses money).
The Worked Example: One Funnel, Every Number
Meet a lead-gen funnel: $10,000 in monthly ad spend plus $2,000 in management fees produces 150 leads; 40% book a call, and 25% of calls close. A customer is worth $5,000 at a 60% gross margin. Now carry it through:
- CPL: $10,000 ÷ 150 = $66.67
- Cost per call: 150 × 40% = 60 calls; $10,000 ÷ 60 = $166.67
- Customers: 60 × 25% = 15
- Media CAC: $10,000 ÷ 15 = $667
- Fully-loaded CAC: $12,000 ÷ 15 = $800
- Margin-adjusted LTV: $5,000 × 60% = $3,000
- LTV:CAC: $3,000 ÷ $800 = 3.8:1 — comfortably above the 3:1 bar
- Revenue ROAS: 15 × $5,000 = $75,000; ÷ $10,000 = 7.5x
Verdict: this funnel works. But notice how much the dashboard version — “7.5x ROAS!” — hides: the $133 gap between media and fully-loaded CAC, and the margin that makes $5,000 of revenue worth $3,000.
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What's Your Breakeven ROAS?
Breakeven ROAS = 1 ÷ gross margin — the return at which a campaign earns exactly nothing. At our example's 60% margin, that's 1 ÷ 0.60 = 1.7x.
So the funnel's 7.5x isn't just “good,” it's 7.5x against a 1.7x bar — a wide, quantified safety cushion. That framing matters because the same 7.5x at a 12% margin would be barely above its 8.3x breakeven. A ROAS is never high or low in isolation; it's high or low relative to the breakeven your margin sets. Compute the bar before you celebrate the number.
How Do You Turn LTV Into Bid Ceilings?
Divide LTV by your target ratio, then walk backward through the funnel. This is the most practical output of the whole exercise — it converts unit economics into numbers you can type into an ad platform.
- Max CAC: $3,000 LTV ÷ 3 (targeting 3:1) = $1,000 per customer.
- Max cost per call: $1,000 × 25% close rate = $250.
- Max CPL: $250 × 40% call rate = $100.
Now every dashboard number has a ceiling to be judged against: leads at $66.67 versus a $100 ceiling means room to bid up and take volume competitors can't afford. Leads at $120 would mean the opposite. This is how you know whether to scale or cut — before the month's revenue report tells you the hard way.
Which Lever Actually Moves Your Number?
Run the sensitivity check: nudge each input and see which one moves the outcome most. It's rarely the one getting all the attention.
In our example, cutting CPL by 10% saves about $1,000 a month. But lifting the close rate from 25% to 30% turns the same 60 calls into 18 customers instead of 15 — three more customers on identical spend, roughly $9,000 in additional margin-adjusted value. Same funnel, different lever, nine times the impact. Most teams grind on the cheapest lever (CPL) because it's the one the ad platform shows them.
The same logic runs an ecommerce funnel — swap leads for orders, close rate for site conversion rate, and customer value for AOV × repeat purchases. The formulas don't change; only the labels do.
Try It: The Full-Funnel Math on Your Numbers
The free ROAS & CAC Calculator runs this entire article on your business in about two minutes:
- Pick your funnel type — lead gen or ecommerce.
- Enter your numbers — spend, management costs, funnel rates, customer value, margin.
- Get the verdict — ROAS versus breakeven, media and fully-loaded CAC, LTV:CAC, your bid ceilings at every stage, and the single biggest lever in your funnel.
No email gate. One honest caveat: the math is only as good as the attribution feeding it — if you're not sure your revenue numbers trace back to the right campaigns, read our CRM attribution guide first, or have us look at the funnel with you.
Frequently Asked Questions
How do you calculate ROAS?
Divide the revenue attributed to your ads by your ad spend: $75,000 in revenue on $10,000 of spend is a 7.5x ROAS. Then compare it to your breakeven ROAS — 1 ÷ gross margin — because a ROAS below breakeven loses money no matter how healthy it sounds.
How do you calculate CAC?
Divide acquisition spend by new customers acquired. Media CAC uses ad spend only; fully-loaded CAC adds management fees and tooling — in our worked example, $10,000 ÷ 15 customers = $667 media CAC, but $12,000 ÷ 15 = $800 fully loaded. Use the loaded number for decisions.
What is a good LTV to CAC ratio?
The commonly used bar is 3:1 — a customer's margin-adjusted lifetime value should be roughly three times their fully-loaded acquisition cost. That leaves room for overhead and profit. Ratios well below 3:1 make growth expensive; far above it may mean you're underspending on acquisition.