Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Paid-only CAC
$150
Blended CAC
$60
Paid ÷ blended dependency ratio
2.50
LTV:CAC on paid alone
3.00
LTV:CAC blended
7.50
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How to use this
- 1Enter total paid marketing spend ($).
- 2Enter new customers attributed to paid.
- 3Enter new customers from organic/referral/direct.
- 4Enter average customer lifetime value ($).
- 5Read your paid-only cac on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
Blended CAC (total spend divided by total new customers) looks healthy when a strong organic or referral engine is doing free work alongside paid media, but it hides whether your paid channels are actually efficient on their own. This calculator splits new customers into paid-attributed and organic/referral-attributed buckets, then computes paid CAC (spend ÷ paid customers only) and blended CAC (spend ÷ all customers) side by side, along with the ratio between them. A wide gap — paid CAC at 3x blended CAC, for example — means your reported 'CAC is fine' story depends heavily on brand equity and word of mouth that paid spend isn't creating and can't easily scale. It also flags what happens to blended CAC if organic share erodes, which matters when you're forecasting the payback math for a funding round or budget request. Use this alongside a proper incrementality test, since organic conversions attributed via last-click can themselves be inflated by paid brand search cannibalizing what would have been a free direct visit.
Worked example
Using the values the calculator loads with:
Inputs
- Total paid marketing spend: 120000 $
- New customers attributed to paid: 800
- New customers from organic/referral/direct: 1200
- Average customer lifetime value: 450 $
Results
- Paid-only CAC: $150
- Blended CAC: $60
- Paid ÷ blended dependency ratio: 2.5
- LTV:CAC on paid alone: 3
- LTV:CAC blended: 7.5
What each field means
Inputs
- Total paid marketing spend ($)
- The total paid marketing spend used in the calculation, measured in $. Starts at 120000 $ so you have a working example on load.
- New customers attributed to paid
- The new customers attributed to paid used in the calculation. Starts at 800 so you have a working example on load.
- New customers from organic/referral/direct
- The new customers from organic/referral/direct used in the calculation. Starts at 1200 so you have a working example on load.
- Average customer lifetime value ($)
- The average customer lifetime value used in the calculation, measured in $. Starts at 450 $ so you have a working example on load.
Results
- Paid-only CAC
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Blended CAC
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Paid ÷ blended dependency ratio
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- LTV:CAC on paid alone
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- LTV:CAC blended
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
What's a healthy dependency ratio?
Under 1.5x means paid is carrying its weight close to the blended average, which is a resilient position. Above 2.5-3x means the business's efficient-looking blended number depends heavily on non-paid channels, and a slowdown in organic growth would expose a much worse true paid economics story.
Why not just report blended CAC to investors?
Blended CAC is fine as a top-line health metric, but it can't tell you whether increasing paid budget will scale efficiently, because organic doesn't scale linearly with paid spend. Decomposing the two tells you the real marginal cost of the next customer you'd acquire by spending more.
How do I know which customers are really organic vs paid-influenced?
Last-click attribution over-credits whichever channel touched the customer last, often organic search after a paid ad created initial awareness. A media mix model or incrementality test gives a more honest split than raw attribution reports.
Does this replace an LTV:CAC calculation?
No, it feeds into one. Once you know paid CAC and blended CAC separately, compare each against LTV to see the real payback economics of paid spend versus the blended story you might be telling internally.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Paid vs. Blended CAC Decomposition Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/paid-vs-blended-cac-decomposition
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/paid-vs-blended-cac-decomposition" target="_blank" rel="noopener">Paid vs. Blended CAC Decomposition Calculator — RevenueLab</a> (2026).</p>
Source: [Paid vs. Blended CAC Decomposition Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/paid-vs-blended-cac-decomposition) (2026).