---
title: "CAC, LTV, Payback: SaaS Unit Economics VCs Actually Care About"
description: "CAC, LTV, and CAC payback are the core SaaS unit-economics metrics. Here's how to compute them honestly and what benchmarks matter for 2026 fundraising."
date: 2026-04-18T00:00:00.000Z
tags: ["vc-explainers", "saas", "unit-economics", "investor-education"]
source: https://venturecapitaltracker.com/what-is-cac-ltv-payback-saas-unit-economics
---

# CAC, LTV, Payback: SaaS Unit Economics VCs Actually Care About

> CAC, LTV, and CAC payback are the core SaaS unit-economics metrics. Here's how to compute them honestly and what benchmarks matter for 2026 fundraising.

If you're raising a SaaS round, VCs will ask about **CAC, LTV, and payback**. Getting these right signals financial maturity; getting them wrong signals otherwise.

### Customer Acquisition Cost (CAC)

**Formula**: (Sales + Marketing spend in period) / (New customers acquired in period)

**Honest calculation includes**:
- Full S&M salary and commissions.
- Ads and demand gen.
- Events and content.
- Tool stack (Salesforce, HubSpot, Outreach).
- Allocated overhead for S&M.

**Common mistakes**:
- Only including paid ads (underreports CAC).
- Including post-sale customer success in sales (overreports CAC).

### Lifetime Value (LTV)

**Formula (simplified)**: ARPA × Gross Margin / Churn

Where:
- **ARPA**: Average Revenue Per Account (annual).
- **Gross Margin**: Typically 75–90% for SaaS.
- **Churn**: Annual revenue churn rate.

**Worked example**:
- ARPA: $12,000
- Gross Margin: 80%
- Churn: 10% annually
- **LTV** = $12,000 × 0.80 / 0.10 = **$96,000**

### LTV:CAC ratio

- **Under 1:1**: You lose money on every customer.
- **1:1 – 2:1**: Marginal.
- **3:1**: Healthy early-stage SaaS.
- **4:1+**: You should invest more in growth.

### CAC Payback Period

**Formula**: CAC / (ARPA × Gross Margin)

**Example**:
- CAC: $20,000
- ARPA × Gross Margin = $12,000 × 0.80 = $9,600/year
- **Payback** = $20,000 / $9,600 ≈ **25 months**

Benchmarks:
- **Under 12 months**: Excellent.
- **12–18 months**: Strong.
- **18–24 months**: Typical for enterprise SaaS.
- **Over 24 months**: Requires exceptional retention to be investable.

### Net Revenue Retention (NRR)

**Formula**: (Starting ARR + Expansion − Churn − Downgrade) / Starting ARR

Benchmarks:
- **>130%**: Exceptional.
- **110–130%**: Strong.
- **100–110%**: Healthy.
- **Under 100%**: Worrying — your base is shrinking.

### Gross vs Net Dollar Retention

- **Gross Dollar Retention (GDR)**: Retention without expansion. Floor: how much of last year's ARR you keep.
- **Net Dollar Retention (NDR/NRR)**: Retention with expansion.

Top investors often weight GDR higher than NRR because expansion can mask bad core retention.

### Cohort analysis

Cohort analysis shows how a group of customers acquired in the same period behaves over time. VCs look at:
- **Revenue retention curves**: Upward curves = expansion > churn.
- **Logo retention**: How many customers remain.
- **Net dollar expansion**: Average $/customer growth in the cohort.

### Red flags

1. **Payback over 24 months** with under 100% NRR.
2. **CAC mostly paid CAC** — little organic pipeline.
3. **LTV inflated by assumed 1% churn** when actual churn is 10%.
4. **No cohort data** — "just trust us."

### Practical takeaway

1. **Founders**: Build a cohort analysis early; it's your primary fundraising weapon.
2. **Investors**: Recompute CAC and LTV from raw data in due diligence. Trust but verify.
3. **Operators**: Plot payback against NRR quarterly — it's the single best health dashboard.

### Further reading

- Bessemer's State of the Cloud: https://www.bvp.com/atlas/state-of-the-cloud-2024

**By:** [Venture Capital Tracker](https://venturecapitaltracker.com/editorial-policy)

**Editorial note:** AI tools assisted with research, structure, or drafting. Venture Capital Tracker retains human editorial responsibility for factual accuracy, relevance, and source quality before publication.