What’s my blended CAC?
Your blended CAC is the single number that tells you how much it costs to acquire an average customer across all channels combined. Here's how to calculate it from your actual data.
The short answer
What is your blended CAC?Take your total sales and marketing spend for the month and divide by the number of new paying customers. That is your blended customer acquisition cost. Sounds simple, but “total spend” lives across ad platforms and accounting, and “new paying customers” lives across your CRM and accounting. Getting both numbers right requires pulling data from multiple systems.
Why your blended CAC is the number investors and lenders ask for first
You spent $6,000 on Google Ads, $1,800 on Meta, $2,400 on a sales rep's time allocated to new business, and $800 on marketing tools. That is $11,000 in total acquisition spend. You gained 16 new paying customers. Your blended CAC is $687.50.
This number matters because it tells you the health of your growth engine. If your blended CAC is rising, you are spending more to grow at the same rate. If your average customer is worth $2,000 in lifetime value and your CAC is $687, your LTV:CAC ratio is 2.9x, which is solid. If your CAC creeps to $1,200, that ratio drops to 1.7x and your business model starts to strain.
The problem is that “total acquisition spend” is scattered across ad platforms, payroll, and software subscriptions. And “new customers” requires distinguishing new buyers from returning ones. Neither number is sitting in a single dashboard waiting for you.
Blended CAC explained: what goes into the calculation
Blended CAC is deceptively simple in concept but tricky in practice. Here is what you need to include:
- Numerator: total acquisition spend. This includes ad spend (all platforms), sales team compensation (pro-rated for new business), marketing tools and software, content creation costs, and any referral fees or commissions.
- Denominator: new paying customers. Not leads. Not trials. Not MQLs. Customers who made a payment this month for the first time. Returning customers do not count.
- Time alignment. The spend in March might produce customers in April or May. Ideally, you would track cohorts (March spend vs. customers acquired from March leads). In practice, most businesses use same-month comparisons as a proxy.
- LTV:CAC ratio. Once you have your blended CAC, divide your average customer lifetime value by the CAC. Below 3:1 is a warning sign. Above 5:1 might mean you are under-investing in growth.
How to calculate blended CAC from ad platforms and accounting (6 steps)
You need spend data from ad platforms, cost data from your P&L, and new customer counts from your CRM and accounting software. About 45-60 minutes.
- 1Total up ad platform spend
Log into Google Ads (Campaigns → Cost column) and Meta Ads Manager (Amount Spent). Add any other paid platforms (LinkedIn, TikTok, etc.). Sum them up.
- 2Add sales and marketing costs from your P&L
In QuickBooks, go to Reports → Profit and Loss. Find your marketing and sales expense categories. Add the portions allocated to new customer acquisition: sales team salary (pro-rated), marketing tools, content costs. In Xero, go to Accounting → Reports → Profit and Loss and do the same.
- 3Sum your total acquisition spend
Ad spend + allocated sales/marketing costs = total acquisition spend for the month. Write this number down.
- 4Count new paying customers
In HubSpot, filter contacts by “Became a Customer Date” within the current month. In Salesforce, filter Opportunities by “Close Date” this month and “Stage = Closed Won.” Cross-check against your accounting: in QuickBooks, look at Sales by Customer Summary and identify which customers are new this month (no prior transactions).
- 5Divide spend by new customers
Total acquisition spend / new paying customers = blended CAC. Example: $11,000 / 16 = $687.50.
- 6Calculate your LTV:CAC ratio
If you know your average customer lifetime value (total revenue per customer over their relationship), divide it by your blended CAC. A 3:1 ratio or higher is generally healthy.
Total time: 45-60 minutes. The hardest part is step 2 (allocating sales and marketing costs) because your P&L does not cleanly separate acquisition costs from retention costs.
What it takes to track blended CAC every month
Once you have the process, the monthly calculation takes about 30-45 minutes. But the accuracy depends on several assumptions: how you allocate shared costs, whether you count customers in the month they signed up or the month they paid, and whether your CRM customer count matches your accounting customer count (it usually will not match exactly).
The bigger issue is trend tracking. A single month's blended CAC is useful but limited. What you really need is the trend: is CAC going up or down? And how does it compare to your customer lifetime value? That requires consistent monthly data over 6-12 months, which is where most manual processes fall apart.
Or get your blended CAC calculated automatically every month
Bottomline pulls your ad spend from every connected platform, identifies acquisition-related costs from your P&L, counts new paying customers (verified against accounting data), and calculates your blended CAC automatically.
The trend tells you something a single month never could: your CAC spiked in January (holiday hangover, fewer buyers), but the overall trajectory is down. That means your acquisition engine is getting more efficient over time. Without monthly tracking, you would have panicked in January and potentially cut spend on channels that were actually improving.