How LTV is calculated
Three things drive it: what a customer spends on a typical order, how often they buy within a period, and how long they keep buying. Multiply those together and you have lifetime revenue. Then apply gross margin, because the money available to fund marketing is profit, not turnover. That last step is the one most often skipped and it is the one that changes the answer most.
There are two honest ways to produce the number. Historical lifetime value looks back at customers you acquired some time ago and adds up what they actually spent — reliable, but only available for cohorts old enough to have finished. Predictive lifetime value projects a young cohort forward from its early behaviour, which is more useful for decisions and much easier to talk yourself into believing.
For a subscription or retainer business the calculation is simpler, because it reduces to the monthly profit per customer and how long they stay. For a business selling once, lifetime value is close to the margin on the first order and no amount of modelling will change that.
Why LTV matters
It sets what you can afford to pay for a customer. Two competitors bidding on the same keyword are not really competing on budget; they are competing on what a customer is worth to each of them. The business whose customers come back can pay more per click, appear more often, and still be profitable — which is why acquisition cost means nothing until this number sits beside it.
It also changes where effort goes. When lifetime value is high, retention work — onboarding, service, reminders, email — usually returns more than another advertising campaign, because you are protecting money you have already paid to acquire.
Common mistakes with LTV
Using revenue rather than margin is the first and most common, and it produces a figure that justifies spending money the business does not have. The second is assuming a customer lifespan the data does not support, which is easy to do when the business is young and no cohort has run long enough to prove anything.
The third is a single company-wide figure. Wholesale and retail buyers, or customers from a discount campaign and customers who came for the brand, can differ so much that one blended number describes nobody. The fourth is treating lifetime value as cash. Profit spread over years cannot pay this month’s advertising invoice, which is why payback matters as much as the total.
How to act on it
Calculate it in gross profit, by cohort, and split by the segments that genuinely behave differently. Recalculate it as retention changes rather than leaving an old figure in the spreadsheet where it slowly becomes fiction.
Use it to set the acquisition cost you are willing to accept, and pair it with how long that cost takes to come back so the target respects your cash position as well as your profit. If lifetime value is lower than you want, look at repeat purchase and pricing before you look at ad budgets — those levers are usually cheaper and they lift every future campaign at once.