CAC: definition, calculation, and LTV/CAC ratio
Updated on February 22, 2026
Quick definition
CAC (Customer Acquisition Cost) represents the total amount invested — in marketing, sales, and operations — to convert a prospect into a paying customer. CAC is a key strategic metric to assess the economic viability of a growth model and to drive the efficiency of commercial investments.
How it works
Formula
CAC = (Total marketing spend + Sales spend) / Number of new customers acquired during the period
Example: €30,000 marketing + €20,000 sales over one quarter, 100 new customers = CAC of €500
It is important to distinguish two variants of CAC:
- Paid CAC — includes only direct advertising spend
- Blended CAC — includes all acquisition costs: salaries, CRM tools, agency fees, content creation
Blended CAC is always higher but more representative of the economic reality. Using only paid CAC leads to underestimating the true acquisition cost and making misguided investment decisions.
The difference between CAC and CPA matters: CPA can measure any conversion (lead, sign-up, download), while CAC specifically measures the cost to acquire a paying customer.
CAC can also be calculated by acquisition channel (SEO CAC, Google Ads CAC, outbound sales CAC) to identify the most efficient sources and direct investments accordingly.
Why it matters
CAC is the foundational building block of the economic model of any growing company. Combined with LTV, it lets you compute the LTV/CAC ratio, the main indicator of an acquisition strategy's health:
- LTV/CAC < 1 — the company is burning cash: each customer costs more than it brings in
- LTV/CAC between 1 and 3 — fragile model, insufficient margins to reinvest
- LTV/CAC > 3 — healthy and scalable model, the standard sought by investors
For startups and SaaS companies in particular, CAC is one of the most scrutinized metrics by investors, as it defines the capital required to grow at a given pace. A high CAC is not necessarily problematic if LTV is proportionally higher.
How to improve or use it
- 1Invest in compounding acquisition channels such as SEO, content marketing, and referral programs — their CAC decreases over time, unlike paid ads.
- 2Optimize your sales process to shorten the sales cycle and reduce the number of touchpoints required to convert.
- 3Improve upstream lead qualification so sales teams focus on high-potential prospects.
- 4Work on organic conversion via reassurance elements, case studies, and social proof to reduce friction in the buying journey.
- 5Track your payback period (CAC / (ARPU × gross margin)) — aiming for under 12 months is the standard for a healthy SaaS.
With Sublim
Sublim helps you precisely calculate your CAC by acquisition channel by accurately attributing conversions to each traffic source. Unlike GA4, which loses part of its conversion data due to cookie restrictions, Sublim provides a more complete collection of acquisition data — giving you a CAC closer to reality and a stronger basis for investment decisions. GDPR-compliant.
Frequently asked questions
What is the difference between CAC and CPA?
CPA (cost per acquisition) measures the cost to obtain any defined conversion (lead, sign-up, download, purchase). CAC (customer acquisition cost) specifically measures the cost to acquire a paying customer, including all related costs (marketing, sales, operations). CAC is therefore a CPA specialized on the conversion to a real customer.
How do you calculate CAC payback period?
The payback period is the time required to recover CAC through revenue generated by the customer. Formula: Payback Period = CAC / (Monthly ARPU × Gross margin %). For example, with a CAC of €600, an ARPU of €100/month, and a 70% margin, the payback period is 600 / (100 × 0.7) ≈ 8.6 months. Aiming for a payback period under 12 months is generally considered healthy for a SaaS.
Should CAC include marketing and sales team salaries?
Yes, blended CAC must include all costs related to acquisition: ad spend, marketing and sales team salaries, CRM and marketing automation tool costs, agency fees, and content creation costs. Using only ad spend gives a partial CAC that underestimates the true acquisition cost and can lead to misguided investment decisions.
Related terms
LTV (Lifetime Value), or customer lifetime value, is the total revenue…
CPA (Cost Per Acquisition) is the cost per acquisition that measures t…
ROI (Return On Investment) is the return on investment that measures t…
ARPU (Average Revenue Per User) is the average revenue per user that m…