CAC and LTV Analytics: How to Calculate Them From Your Traffic Data

By Emily Redmond, Data Analyst at Emilytics · April 2026

TL;DR: CAC = total marketing spend ÷ new customers. LTV = ARPU × average customer lifespan. Goal: 3:1 LTV:CAC ratio or higher.

CAC (Customer Acquisition Cost) and LTV (Lifetime Value) are the two metrics that determine if your SaaS will survive.

If CAC is $1,000 and LTV is $800, you're going broke in slow motion. If CAC is $800 and LTV is $4,000, you're printing money (until you scale).

Most founders calculate both wrong. Here's how to get them right.

Calculate CAC (Customer Acquisition Cost)

CAC = Total marketing spend in a period ÷ New customers acquired in that period

The trick is: include all marketing spend, not just ads.

CAC Formula (Correct Version)

Include:

• Paid ads (Google, Facebook, LinkedIn)
• Marketing tools (email, content management, design)
• Content creation (salaries of marketers creating content, videos, etc.)
• SEO tools (Ahrefs, SEMrush)
• Landing page builders
• Sponsorships
• Event attendance
• Sales team cost (for sales-led SaaS)

Exclude:

• Product development
• Customer support
• Infrastructure costs

Example CAC calculation:

Month 1 spend:

• Google Ads: $5,000
• Email/marketing platform: $500
• Content writer salary (1/4 of time): $2,500
• LinkedIn ads: $1,500
• SEO tools: $200
• Total marketing spend: $9,700

New customers acquired that month: 50

CAC = $9,700 ÷ 50 = $194 per customer

💡 Emily's take: Founders usually forget employee costs. If you pay a marketer $100k/year, that's $8,333/month in CAC. If they generate 20 customers, that's $8,333 ÷ 20 = $416 CAC. Include it.

CAC by Channel

Your overall CAC is useful, but segmented CAC is actionable.

Track by traffic source:

Insight: Organic and direct are "free" (no paid spend). Paid ads and content have costs. If paid ads are your only scalable channel, your CAC will go up as you spend more (law of diminishing returns).

Track CAC in GA4

GA4 doesn't calculate CAC directly (you need billing data), but you can track the denominator (customers acquired):

1. Create custom event customer_acquired (when payment goes through)
2. Track utm_source, utm_medium, utm_campaign
3. Count customers acquired per campaign in GA4 reports

Then calculate CAC in spreadsheet: Spend ÷ GA4 customer count.

Calculate LTV (Lifetime Value)

LTV = Average Revenue Per User (ARPU) × Customer Lifespan

Or more precisely:

LTV = (ARPU × Gross margin %) ÷ Monthly churn rate

LTV Formula (Step by Step)

Step 1: Calculate ARPU (Average Revenue Per User)

Total MRR ÷ Number of customers = ARPU

Example:

• MRR: $50,000
• Customers: 500
• ARPU = $100/month

Step 2: Calculate gross margin

(Revenue - Cost of goods sold) ÷ Revenue

For SaaS, COGS is usually low (hosting, payments processing, support). Assume 70–85% gross margin.

Example: $100 ARPU × 75% gross margin = $75 contribution per customer

Step 3: Calculate monthly churn rate

Customers lost in month ÷ Customers at month start

Example: 500 customers, 25 churn = 5% monthly churn

Step 4: Calculate customer lifespan

1 ÷ Monthly churn = Average months until churn

Example: 1 ÷ 0.05 = 20 months lifespan

Step 5: Calculate LTV

ARPU × Gross margin % × Customer lifespan = LTV

Example: $100 × 75% × 20 months = $1,500 LTV

LTV by Customer Segment

Your blended LTV is useful, but segment LTV tells you which customers are worth acquiring:

Insight: Enterprise customers are worth 30x more than Starter. Your CAC can be higher for Enterprise (pay more to acquire).

Track LTV in GA4

GA4 can't calculate LTV directly (you need billing cohort data), but you can track adoption patterns that correlate with LTV:

1. Create cohorts by signup date
2. Track retention (customers still active at month 6, 12, 24)
3. Correlate with activation speed, feature usage, team size

Example:

Faster activation = longer lifespan = higher LTV.

The LTV:CAC Ratio

This is the metric that determines viability.

LTV:CAC = 3:1 or higher is healthy

Healthy:

• LTV $1,500, CAC $500 = 3:1 ratio ✓

Broken:

• LTV $1,500, CAC $1,200 = 1.25:1 ratio ✗

What ratios mean:

💡 Emily's take: Most SaaS founders obsess over growing CAC. Wrong. If your ratio is 1.5:1, you should raise CAC (or lower it strategically). The ratio matters more than the absolute number.

How to Improve Your LTV:CAC Ratio

To improve LTV:

• Increase ARPU (raise prices, upsell, add features)
• Reduce churn (improve activation, product quality)
• Extend customer lifespan (expand revenue, add more users to account)

To improve CAC (lower it):

• Focus on channels with lower CAC (organic > paid)
• Improve conversion rate (optimize funnel)
• Reduce marketing spend waste (stop ineffective campaigns)

Example: Improving the Ratio

Start: LTV $1,000, CAC $800, ratio 1.25:1 (bad)

Option A: Reduce CAC by 20%

• New CAC: $640
• Ratio: 1.56:1 (better, but still risky)

Option B: Increase LTV by 50% (raise prices, reduce churn)

• New LTV: $1,500
• Ratio: 1.88:1 (healthier)

Option C: Both (reduce CAC 20%, increase LTV 30%)

• New CAC: $640
• New LTV: $1,300
• Ratio: 2.03:1 (sustainable)

Which to do? Usually increase LTV first (improve product, reduce churn). Then reduce CAC as a secondary optimization.

Frequently Asked Questions

Q: What if my CAC changes by channel?

A: Yes, it should. Organic CAC is $0. Paid ads might be $300. Enterprise sales might be $1,500. Calculate separately and decide which channels to invest in.

Q: Should I use gross margin or net profit in LTV calc?

A: Use gross margin (before operating costs). You need LTV to cover CAC and operating expenses. If LTV is only 2x CAC, you're breakeven on unit economics, not profitable overall.

Q: How often should I recalculate CAC and LTV?

A: CAC monthly (it's fast to calculate). LTV quarterly (needs 3+ months of cohort data to be meaningful).

Q: What if my CAC is above my LTV?

A: You're not viable. Either lower CAC (stop spending on acquisition) or increase LTV (improve product/pricing). This is a critical problem.

Q: How do I benchmark my LTV:CAC ratio against competitors?

A: You can't see their actual numbers. Use this rule: VC-backed SaaS targets 3:1. Bootstrap SaaS targets 4:1+ (lower risk tolerance). If you're below 2:1, you're behind peers.

CAC + LTV in Your Weekly Dashboard

Add these to your weekly review:

Rising CAC + falling LTV = problem. Investigate.

The Bottom Line

Calculate CAC accurately (include all marketing spend). Calculate LTV honestly (use real churn, real lifespan).

Target 3:1 LTV:CAC ratio. If you're below 2:1, fix it. If you're at 4:1 or higher, you can scale confidently.

Emily Redmond is a data analyst at Emilytics — AI analytics agent watching your GA4, Search Console, and Bing data around the clock. 8 years experience. Say hi →