---
type: method
slug: unit-economics-cac-ltv
title: "Calculate unit economics (CAC, LTV, payback)"
category: "Finance & Accounting"
subcategory: "Planning & modelling"
level: intermediate
source: https://deepstoryresearch.com/method/unit-economics-cac-ltv
publisher: Deepstory Research
---

> **How to use this file:** attach it to ChatGPT, Claude, Gemini or Copilot (or paste the prompt section), replace every [PLACEHOLDER] with your details, and add any data or Deepstory evidence files the method needs.

## When to use this method
- Deciding whether to scale paid acquisition.
- Investors ask about unit economics.

## Prompt

# Calculate unit economics (CAC, LTV, payback)
Method by Deepstory Research: deepstoryresearch.com/method/unit-economics-cac-ltv

You are a growth-finance analyst. Follow the method below step by step. Goal: Customer acquisition cost, lifetime value, gross-margin payback and what to change to improve them.

## My inputs
- Marketing and sales spend: [MARKETING_AND_SALES_SPEND]  (example: last 6 months by channel)
- New customers: [NEW_CUSTOMERS]  (example: by month and channel)
- Revenue per customer and gross margin: [REVENUE_PER_CUSTOMER_AND_GROSS_MARGIN]  (example: ₹1,200/month at 70%)
- Churn or retention: [CHURN_OR_RETENTION]  (example: monthly churn 4%)

Before you start: if any input above is still in [BRACKETS] or missing, ask me for it in one short numbered list and wait. Do not guess. If I attached files (data, briefs, Deepstory evidence files), treat them as the primary source.

## Steps to follow
1. Compute blended and per-channel CAC.
2. Compute LTV using gross margin and churn (show formula).
3. Compute LTV:CAC and payback months.
4. Segment by channel or cohort if data allows.
5. Recommend where to scale, fix or cut.

## Deliver the output in this structure
- Metric table with formulas
- Channel comparison
- Cohort view
- Recommendations

## Quality rules
- Use gross margin, not revenue, in LTV.
- Warn if cohorts are too young to trust churn.
- Label every number as FACT (with source and date), ESTIMATE (show the calculation) or ASSUMPTION.
- If a Deepstory evidence file is attached, use its figures as the reference values and cite its source references; tag claims that are not from it as [UNVERIFIED].
- End with: the 3 assumptions that matter most, what would change the answer, and the single best next step.

## Evidence you can attach
- Six-Economy Macro Baseline: https://deepstoryresearch.com/data/global-macro-baseline (AI context file: https://deepstoryresearch.com/context/global-macro-baseline.md)
- US Inflation & the Fed: https://deepstoryresearch.com/data/us-inflation-fed (AI context file: https://deepstoryresearch.com/context/us-inflation-fed.md)
- Private Credit: A $1.2 Trillion Disagreement: https://deepstoryresearch.com/data/private-credit-growth (AI context file: https://deepstoryresearch.com/context/private-credit-growth.md)

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Deepstory methods are process guidance for AI tools. Review AI output before relying on it; legal, tax, medical and investment matters need a qualified professional.