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Practical guide to subscription unit economics: formulas, workflow, implementation pitfalls, and a direct execution playbook with Unit Economics Calculator.
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Scenario modeling for CAC, LTV, margin, and net profit with growth lever prioritization.
Lifetime Value is the total gross profit a customer generates before they churn. For subscription businesses with relatively stable churn:
LTV = ARPU x Gross Margin / Monthly Churn Rate
This is the simplified steady-state formula. It works when churn is consistent month-over-month.
LTV = $49 x 0.80 / 0.03 = $39.20 / 0.03 = $1,307
Churn is the denominator, so small movements create outsized LTV swings:
| Monthly Churn | LTV | Change vs 3% |
|---|---|---|
| 2% | $1,960 | +50% |
| 3% | $1,307 | baseline |
| 4% | $980 | -25% |
| 5% | $784 | -40% |
| 7% | $560 | -57% |
Going from 3% to 5% churn destroys 40% of your LTV. This is why retention work often has higher ROI than acquisition work.
The standard benchmark: LTV:CAC > 3:1.
With LTV = $1,307 and CAC = $300, your ratio is 4.4:1 — healthy. But if churn rises to 5%, LTV drops to $784 and the ratio falls to 2.6:1 — below target. You would need to cut CAC to $261 or raise ARPU to maintain the 3:1 floor.
To cover fixed costs, you need:
Break-even subscribers = Fixed Costs / (ARPU x Gross Margin)
Example: $25,000/month in fixed costs (team, office, tools) with ARPU = $49 and 80% margin:
$25,000 / $39.20 = 638 paying subscribers to break even.
Model your own churn scenarios in the Unit Economics Calculator. See also: Cohort LTV Modeling for SaaS.
This material is for informational purposes only. Results from this article and tool are approximate estimates, not financial, tax, legal, or investment advice. Actual payments, APR, taxes, fees, and eligibility depend on your lender, jurisdiction, and personal profile. Confirm key decisions with official disclosures and a licensed professional.
This article is reviewed by the Tools Hub editorial team for factual accuracy, practical relevance, and consistency with current product workflows.
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