Lifetime value (LTV) is the total profit a customer relationship delivers before it ends. It's the number that justifies acquisition spend, reveals which customers deserve the red carpet, and puts a dollar figure on retention work. It is also the most routinely inflated number in small business — a fantasy LTV "justifies" a CAC that quietly bankrupts you. This lesson is the honest version.
LTV = average contribution per purchase × purchases per year × years retained.
The detailing customer: $104 contribution per job, books 6 times a year, sticks around 2.5 years on average → LTV ≈ $1,560.
The three honesty rules, in order of how often they're broken:
Set honest LTV next to CAC and you get the exchange rate of your growth machine: LTV:CAC. Spend $125 to acquire $1,560 of lifetime contribution and the ratio is ~12:1 — every acquisition dollar returns twelve. At 12:1, underspending on acquisition is the mistake. At 1.5:1, the machine barely covers its fuel — and since your LTV arrives over years while CAC is paid today, a thin ratio plus growth equals a cash crisis on a schedule (payback period, next lesson, is that exact clock).
A common rule of thumb says 3:1 is a healthy floor for a subscription-style business. Treat it as folklore, not physics — the right floor depends on how fast the LTV arrives and how much cash you have to float the gap. The direction is what's certain: higher is better, and a ratio you haven't computed is the same as not knowing whether growth makes you richer.
Retention gets a price tag. If adding half a year of average retention adds ~$300 of LTV per customer, then a follow-up system, a reminder cadence, a small loyalty perk — things costing a few dollars per customer — stop being "nice touches" and start being the highest-ROI spend in the company. You can now compute that, instead of asserting it.
Frequency is an LTV lever too. Moving the 6-visits-a-year customer to 7 (a booking cadence, a seasonal package) adds $104 × years retained per customer — often cheaper to engineer than any new-customer campaign. The three LTV inputs — contribution, frequency, duration — are three separate dials, and most owners only ever push on "more customers," the dial that isn't in the formula.
Your best customers become visible. Rank customers by realized contribution-to-date and the top decile usually funds a shocking share of the business. Serve them accordingly: priority scheduling, first access, actual thank-yous. The red carpet is cheap and the math says exactly who gets it.