SaaS unit economics: calculate LTV and CAC by sales channel

For SaaS founders, understanding unit economics is vital for ensuring profitable growth and efficient scaling. This is a “must-have” for both business decisions and fundraising. Unit economics differs across acquisition channels and includes specific marketing and sales costs depending on the model. Let’s dive into the details of LTV and CAC calculation and see how unit economics influences the overall financial model of a business.

Unit economics measures how much you’re spending to acquire a customer versus how much revenue that customer generates over their lifetime. These insights are crucial for fine-tuning pricing, marketing, and sales strategies. In this article, we’ll explain unit economics for self-service, inbound sales, and outbound sales models, and show how to calculate these metrics for a scalable SaaS business.

Unit economics measures the revenue and costs associated with acquiring and retaining a single customer. The two key metrics are:

• Customer Lifetime Value (LTV): The total revenue a customer is expected to generate over their lifetime.
• Customer Acquisition Cost (CAC): The total cost to acquire that customer, including marketing, sales, and outreach expenses.

A strong SaaS business should aim for an LTV/CAC ratio of at least 3:1, meaning you generate three dollars for every dollar spent acquiring a customer. A 1:1 ratio doesn’t work because CAC includes only the direct expenses of acquisition. To cover all variable and fixed costs and reach break-even, a higher ratio is needed.
SaaS products usually have subscription plans for different target audience segments and multiple customer acquisition channels. The typical models are self-service, inbound sales, and outbound sales. Let’s dive into how unit economics differs across these models and how to calculate them using the financial model.

The self-service model is common for B2C customers or small businesses, where users sign up without interacting with a sales team. This model typically has a lower CAC because there’s no direct sales involvement, but LTV might be lower due to higher churn rates and lower prices.

CAC Calculation: CAC for self-service is driven by marketing expenses, such as paid ads or SEO. For example, if you spend $3,000 on marketing and acquire 5 customers:

LTV Calculation: LTV is based on the monthly subscription price and the customer’s lifetime (1 ÷ churn rate). If you charge $100/month and your churn rate is 15%, the customer lifetime is:

LTV/CAC Ratio: To determine profitability:

This ratio shows you’re just breaking even on a customer, but to cover all expenses and grow, aim for a ratio closer to 3.
Self-service is ideal for B2C customers or small businesses who prefer a low-touch, automated purchasing experience.

Above you can see the screenshot from a SaaS financial model, where unit economics is calculated in dynamics. Any company needs some time to test and master its marketing channels and customers engagement. The financial model is more reliable if we reflect this dynamics there.

In inbound sales, B2B customers are generated through content marketing, advertising, and other lead generation efforts, then converted by a sales team. CAC is higher due to both marketing spend and sales team costs, but LTV is also higher because B2B customers tend to sign longer contracts and choose higher-priced plans.

CAC Calculation: CAC includes both lead generation costs and sales team costs. For example:
Marketing spend: $10,000/month, generating 50 leads, gives a CPL (Cost Per Lead) of:

Sales conversion: If 10% of leads convert to paying customers, and you have 5 new customers, factor in the sales team salaries. If 2 inbound sales managers earn $5,000/month each, the total sales team cost is:

Total CAC becomes:

LTV Calculation: For B2B customers, if the subscription price is $200/month and the churn rate is 10%, LTV is:

LTV/CAC Ratio:

This ratio shows a situation where the company is losing money, and revenue doesn’t cover the direct acquisition costs. Optimization in lead generation or sales conversion is needed.
To create a realistic financial model, include the performance of inbound sales managers in calculations. If each manager can handle 30–50 leads, hire more as lead volume grows.
On the screenshot from a SaaS financial model you can see how to include sales managers KPI to the input data. Using this projections we can calculate the number of inbound sales managers based on leads inflow and target KPI.

Inbound sales targets small to mid-sized B2B clients, who need more engagement through educational content and relationship-building before converting. SaaS products can have more expensive plans for this segment and offer additional services like integration into existing client infrastructure.

Inbound sales targets small to mid-sized B2B clients, who need more engagement through educational content and relationship-building before converting. SaaS products can have more expensive plans for this segment and offer additional services like integration into existing client infrastructure.

Outbound sales typically targets enterprise clients, where CAC is the highest due to a direct sales force, longer sales cycles, and significant outreach costs. However, LTV could be much higher because enterprise clients often commit to larger, longer-term contracts.

The core of outbound CAC includes sales team costs, but companies should not underestimate additional costs, which vary based on the target audience and product.
Sales Team Costs: If a sales rep earns $6,000/month and closes 2 deals, CAC is:

However, the outbound team often requires costly additional instruments to reach potential customers.

• Lead Generation Tools: Outbound teams rely on tools like LinkedIn Sales Navigator or ZoomInfo to find and contact leads.
• Business Events & Conferences: Attending industry events to meet enterprise clients can cost a lot, including registration, travel, and accommodations.
• Client Meetings: Despite online meeting play a key role nowadays, In-person meetings also can be a thing and involve travel and hospitality costs.
• Demo and Proposal Costs: Developing custom demos or proof-of-concept trials can add extra costs.

Factoring in these extra expenses provides a more accurate picture of CAC for enterprise clients. For example:

If you spend:

• $6,000 on sales team salaries
• $500 on lead generation tools
• $4,000 on event participation
• $1,000 on client meetings and demos

And close 2 enterprise clients, your CAC is:

LTV Calculation: If your subscription price for enterprise clients is $500/month and churn is 5%, LTV would be:

LTV/CAC Ratio:

Outbound sales often focus on enterprise clients with complex needs, larger deal sizes, and longer contracts. These clients justify higher acquisition costs because of their greater lifetime value. You can also generate additional revenue through integration and customization services.

Tracking and understanding these detailed costs allows you to make informed decisions about scaling your sales, pricing services, and allocating resources.
Your break-even point depends on achieving a favorable LTV/CAC ratio. If CAC is too high, it takes longer to recover the cost of customer acquisition. The SaaS Subscription Financial Model projects when your company will break even by factoring in revenue streams and CAC.
With this knowledge, you can allocate resources more effectively. As inbound leads grow, ensure you have enough salespeople to handle them and avoid bottlenecks. If your self-service model has a high LTV/CAC ratio, invest more in marketing to scale faster.

Investors closely analyze LTV/CAC ratios to assess whether a SaaS business can scale profitably. A ratio of 3:1 or higher signals that the business can generate healthy returns. Investors also look at payback periods, which reflect how quickly a company recovers acquisition costs.
For early-stage startups without commercial traction, proving the business model and showing positive unit economics is crucial during fundraising. Projections of LTV and CAC, along with target metrics, play a key role in securing seed funding. In later rounds, a high LTV/CAC ratio significantly influences the investment decision.

Mastering unit economics is essential for SaaS founders. The examples and screenshots above show how CAC, LTV and the LTV/CAC ratio can be calculated across acquisition channels and used to test pricing, sales capacity and growth assumptions.

For a broader forecast, read the guide to building a SaaS financial model, or explore more finance and business articles on the blog.