What does a new customer really cost you?
Blended CAC is total marketing spend divided by new customers won in the same period, across every channel. It needs no attribution model: spend and new-customer counts are both facts. Divide margin LTV by blended CAC and you get LTV:CAC, the ratio that tells you whether a customer returns more lifetime margin than they cost to acquire.
Ad spend, affiliate and promo across every channel, for the period. From each platform's billing report.
Customers whose first ever order landed in the period. From your order platform, first-timers only.
Lifetime value computed on contribution margin, not revenue. Build yours with the margin LTV calculator.
The only inputs on this page that need an attribution call. Leave blank to skip.
Paid media spend, and the new customers your attribution assigns to paid.
New customers attributed to paid channels.Each new customer cost $40.00 and returns $72.00 of lifetime margin.
LTV:CAC at your blended CAC, then with CAC shifted ten and twenty percent either way. Computed from your inputs, nothing assumed.
Every number is already in your stack
Nothing here needs a data team. Two facts come straight out of tools you open every day, and only the optional paid split ever asks you to trust an attribution model.
One calendar month works. Use the last finished month, not the running one, so spend and new-customer counts are both final.
Sum the period's spend from every ad platform's billing report, then add affiliate and promo for the same window. All channels, one number.
From your order platform's customer report: customers whose first ever order landed in the period. Returning customers are excluded.
Want paid CAC beside the blend? Add paid spend and the new customers your attribution assigns to paid. This is the only input that needs an attribution call.
Bring lifetime value computed on contribution margin, not revenue. The margin LTV calculator builds it from AOV, purchase frequency, lifespan and CM%.
The whole method is two facts divided
Most definitions you will find rank for B2B SaaS: sales salaries in the numerator, contracted annual recurring revenue in the denominator. A DTC brand needs neither. Blended CAC divides two facts you already have, and only per-channel CAC ever needs an attribution model.
Same definitions as The Math. Margin LTV is computed on contribution margin, not revenue: LTV = AOV × purchase frequency × customer lifespan × CM%, where the margin is what survives after discounts, landed COGS (cost + freight-in + duty), shipping and fulfilment, and payment and platform fees: the contribution margin before marketing.
Over one period you spent $10,000 across every channel and won 250 new customers. Blended CAC is $10,000 ÷ 250 = $40.00. Two facts, one division, and no attribution model anywhere in it.
Each of those customers carries $72.00 of margin LTV, so the ratio is $72.00 ÷ $40.00 = 1.8 : 1. Every customer acquired in the period returns $32.00 more lifetime margin than they cost.
These are your live inputs from the calculator above, not a canned example. Change a number up there and this paragraph follows.
The first honest read on acquisition
Blended CAC and LTV:CAC are whole-business numbers. They do not tell you which campaign to touch; they tell you whether acquisition as a whole is creating or destroying lifetime margin, and they do it before any attribution debate can start.
One ratio answers the first question: does a dollar of marketing create more lifetime margin than it consumes? Everything about channels, campaigns and creative comes after that answer, not before it.
Both inputs are facts, so the trend is real. When blended CAC moves, something in the business moved: spend, mix or conversion. It cannot be an artifact of an attribution window change, because there is no attribution in it.
CAC payback (months) = CAC ÷ monthly contribution margin per customer. Margin tells you if. Payback tells you when. Both clocks start from the CAC you just computed.
Where the blended average stops
Blended CAC is where we start every acquisition conversation, and it is the wrong tool for the next question. Here are both halves, honestly.
Spend and new-customer counts are both facts, so any operator can compute it in a minute and no platform can inflate it.
Every channel, every touchpoint, one number. If acquisition is underwater at the blend, no channel-level story changes that.
The definition never shifts under you the way platform-reported CAC does when attribution settings or windows change.
The blend hides winners and losers by construction. Splitting CAC by channel needs an attribution model, and that is a different, softer number.
Blended CAC is the average of the last cohort. Marginal CAC = Δspend ÷ Δcustomers: the cost of the next cohort, not the average of the last, and the only CAC that governs the scale decision.
A strong organic month can hold blended CAC steady while paid acquisition quietly deteriorates underneath it.
From one average to every dimension
When the decision is channel-shaped or scale-shaped, an average is the wrong instrument. Blufire S2 Unit Economics computes CAC, NCAC, CM-payback and LTV:CAC from reconciled orders, and Marginal CAC & Saturation shows the cost of the next customer, which is what actually governs scale decisions. In one demonstrative channel, blended CAC across five spend tranches is about A$82 while the fifth tranche runs A$263. Same account, same month.
Run it monthly, read the trend
A blended number is a period ritual, not a live dashboard. Run it on closed months, watch the trend, and let two trigger lines force the next question.
Recompute on the last closed calendar month, once spend and new-customer counts are final. Read the three-month trend, not one month: a single month mixes launches, promos and seasonality.
Rerun the numbers before you add spend. The blend prices the average customer of the last period, not the next one, so treat it as the entry check rather than the green light.
At or below 1 : 1, acquisition is underwater before fixed costs: margin, retention or price has to move before spend does. And when blended CAC climbs while margin LTV holds, find which cost or mix moved before adding budget.
Questions operators ask
No, and that is the point. Total marketing spend comes from your ad platforms' billing, and new-customer counts come from your order platform: both are facts. Attribution only enters when you try to split CAC by channel, which is why the paid CAC inputs on this page are optional.
Because they are written for B2B SaaS, where customers are acquired by sales teams and measured in contracted annual recurring revenue. A DTC brand acquires through marketing, so the honest numerator is total marketing spend for the period, ad spend, affiliate and promo included, and the denominator is new customers, not contracts.
A customer whose first ever order landed in the period. Returning customers are excluded: they were acquired in an earlier period, and counting them again flatters CAC. Your order platform's first-time customer flag is the source.
Margin LTV. LTV = AOV × purchase frequency × customer lifespan × CM%, computed on contribution margin, not revenue. Revenue LTV compares a gross number to a real cost and overstates the ratio: a customer only ever repays acquisition out of margin.
The only line the math itself gives you is 1 : 1: below it, every customer costs more than they ever return in margin. Above it, the answer depends on payback timing and your fixed-cost base, not on a universal target. CAC payback (months) = CAC ÷ monthly contribution margin per customer. Margin tells you if. Payback tells you when.
Because the blend spreads all spend across all new customers, including the ones who arrived organically. Paid CAC divides paid spend by only the customers your attribution assigns to paid, so the gap between the two numbers is roughly the organic subsidy hiding inside the blend.