Average Revenue Per User (ARPU)vsLifetime Value (LTV)

ARPU measures the average revenue generated per user or account over a specific period — typically monthly. If your SaaS earns $100K/month from 500 users, your ARPU is $200/month. ARPU is the simplest lever for growth: increasing ARPU by 20% has the same revenue impact as increasing your customer count by 20%, but without the acquisition cost. Slack's ARPU grew from $12 to $18/month per paid user by adding premium features, driving 50% revenue growth without proportional customer growth.

Lifetime Value is the total revenue you can expect from a single customer over the entire duration of your relationship. It is the most critical number for understanding how much you can afford to spend on acquiring customers. The simplest formula: LTV = ARPU ÷ Monthly Churn Rate. A customer paying $100/month with 5% monthly churn has an LTV of $2,000. Netflix's LTV exceeds $1,200 per subscriber because churn is below 2.5% — this justifies their $17B+ annual content spend. LTV is the roof of your building: it determines the maximum CAC you can afford, the features you can build, and the team you can hire.

The trap is treating ARPU as a single number when it's actually a blend of wildly different segments. If 80% of your users pay $10/month and 20% pay $500/month, your ARPU is $108 — a number that represents nobody. The $10 users are being over-served relative to their revenue, and the $500 users are likely under-served. Flying blind on a blended ARPU hides your real business: you're running two products at two price points.

Most founders massively overestimate LTV by assuming customers will stay forever. In reality, early-stage startups have limited cohort data. A startup with 6 months of history claiming $3,000 LTV is extrapolating a trend that hasn't been validated. Use conservative estimates (12-24 months cap) until you have 3+ cohorts with 12+ months of data. Also, LTV should be calculated on gross margin, not revenue — a $2,000 LTV with 50% gross margin means only $1,000 in actual profit to cover acquisition costs.

Calculate ARPU by segment, not just in aggregate. Split customers into at least 3 tiers (e.g., Starter, Pro, Enterprise) and track ARPU for each. Then identify your highest-ARPU segment and ask: 'How do I get more customers like THIS?' Track ARPU trend monthly — is it increasing (good: upsells working) or decreasing (bad: you're acquiring cheaper customers or discounting too aggressively)?

Calculate LTV two ways: (1) Simple: ARPU ÷ Monthly Churn Rate. (2) Cohort-based: track actual revenue from each monthly cohort over time. Compare them — if your cohort LTV is lower than your formula LTV, your churn rate is misleading you (possibly due to early-life churn spikes). Always report Gross Margin-adjusted LTV: LTV × Gross Margin. This is the number that matters for unit economics.