How do you calculate 'true' LTV when you have variable churn by cohort age, and some customers never expand?
Brief
Cohort-based LTV = ARPU × cohort retention curve ÷ discount rate. Don't use blended churn. Plot retention by age, calculate LTV per cohort, weight by composition. Variable expansion = manual scenario tables.
Detail
Standard LTV formula (ARPU ÷ monthly churn) assumes flat churn forever. Reality: churn is highest in months 1-3, then stabilizes. Some cohorts expand; others don't. Here's how to model actual LTV:
Step 1: Build Cohort Retention Curves Track each cohort monthly. Plot retention degradation:
- Cohort A (2024): Month 1 100%, Month 2 95%, Month 3 92%, Month 6 85%, Month 12 78%
- Cohort B (2025): Month 1 100%, Month 2 96%, Month 3 93%, Month 6 87%, Month 12 80%
Don't blend; retention improves over time as your product matures.
Step 2: Estimate Expansion by Cohort Some cohorts never expand (SMB self-serve). Enterprise cohorts expand 15-25% annually. Track separately:
- Cohort A (SMB): 0% expansion, $1K ARPU
- Cohort B (enterprise): 20% expansion, $10K ARPU, +$2K annual uplift
Step 3: Calculate Cohort LTV Formula: LTV = Sum of (ARPU × retention_month) + expansion_upsells
Example (24-month view, no discount rate): ``` Cohort A (SMB, $1K ARPU, 0% expansion): Month 1-12: $1K × (100% + 95% + 92% + ... + 78%) = $1K × 10.8 = $10.8K Month 13-24: $1K × (77% + 75% + ... + 68%) = $1K × 8.9 = $8.9K Total LTV (24m): $19.7K
Cohort B (Enterprise, $10K ARPU, 20% expansion/year): Month 1-12: $10K × 12 months baseline + $2K expansion (month 9+) = $122K Month 13-24: $11.2K × 12 months (expanded ARPU) = $134K Total LTV (24m): $256K (2.5x higher due to expansion) ```
Bridge Group research: Companies with variable expansion by segment show 50-100% LTV variance across cohorts. Blended average hides this.
Step 4: Weight by Current Cohort Mix If your revenue is 60% SMB (LTV $19.7K) and 40% enterprise (LTV $256K): `` Blended LTV = (0.60 × $19.7K) + (0.40 × $256K) = $11.8K + $102.4K = $114.2K ``
Discount Rate Adjustment (for present value): If you apply 10% annual discount rate (investors expect capital return): `` Present Value LTV = LTV ÷ (1 + discount_rate)^n Cohort A PV: $19.7K ÷ 1.10^2 = $16.3K Cohort B PV: $256K ÷ 1.10^2 = $211.6K Blended PV: $127.9K ``
This is the LTV you should use for board reporting; it's more conservative than un-discounted.
Operator moves:
- Build cohort retention in Excel or BI tool (Tableau, Looker); don't hand-calculate
- Segment LTV by product line (if multi-product), geography, and buyer persona
- Run sensitivity: If churn increases 5pp, how does LTV change?
- Board narrative: "Our LTV:CAC is 4.2:1 using present-value LTV with segment-specific expansion. This accounts for variable churn by cohort and actual expansion patterns."
- Flag if any cohort has LTV:CAC <2.5:1; investigate unit econ risk
TAGS: LTV,cohort-analysis,churn-modeling,expansion-revenue,board-metrics