How this instrument works
Customer lifetime value converts a single purchase into a relationship-length estimate of profit. Average order value times purchases per year gives one year of revenue from a typical buyer; multiplying that by gross margin turns revenue into the profit actually kept after cost of goods; multiplying again by the average years a customer keeps buying projects that annual profit across the whole relationship. The four inputs are chosen because each is something most billing systems or point-of-sale reports already track, so the output can be produced without a custom cohort study.
A marketing lead running paid acquisition uses this figure as a spending ceiling: money spent winning one customer should stay well below the gross profit that customer is expected to return, leaving room for overhead and for the customers who churn before turning a profit at all. A founder preparing unit economics for investors reports the same number next to customer acquisition cost, because the ratio between the two is one of the first things a reviewer checks before looking at revenue growth.
The model assumes flat behavior for the entire lifespan — the same order size, buying frequency and margin every year — and it does not discount later years' profit back to present value or separate long-tenure loyal customers from ones who churn early. A retail chain and a subscription app both fit the same four numbers, but neither gets a churn curve or a cohort breakdown here; treat the result as a single-number approximation, not a forecast for any one customer.
- Enter Average order value, $ for what a typical customer spends per purchase.
- Set Purchases per year to how many times that customer buys from you annually.
- Enter Gross margin, % — profit remaining after cost of goods, not your markup percentage.
- Set Average customer lifespan, years to how long a customer keeps buying on average.
- Read Customer lifetime value — the gross profit one customer relationship is projected to return.
Worked example — a $60 order, four times a year
Take a customer who spends $60 per order, buys four times a year, at a 50% gross margin, and stays a customer for 3 years on average. Multiply: 60 × 4 × 0.50 × 3 = 360. That $360 is not revenue — it is the gross profit this one customer relationship is expected to generate across three years, before any money is spent winning or keeping them.
This is why a marketing team treats the figure as a ceiling rather than a target: if acquiring that same customer costs $150 in ads and onboarding, the $360 gross-profit runway comfortably covers it with margin left for overhead; an acquisition cost near $400 would erase the customer's value before they ever turned a profit for the business.
Questions
What is customer lifetime value actually measuring?
It is the gross profit one customer is expected to generate over the full span of the relationship, not their total revenue. Multiplying average order value by purchase frequency gives annual revenue per customer; multiplying by gross margin converts that to profit; multiplying by lifespan projects it across the years they keep buying. It answers one question: how much profit does a typical customer return before the relationship ends?
Why does gross margin matter more than revenue here?
Revenue overstates what a customer is worth because it ignores what it costs to fulfil the order. A $60 order at 50% gross margin returns $30 in profit, not $60, and that $30 figure is the one worth comparing against acquisition cost. Using revenue instead of margin is the most common way a business overstates lifetime value and then overspends chasing customers who never actually pay back the cost of winning them.
How does this relate to the CAC-to-LTV ratio investors ask about?
This instrument produces the LTV half of that ratio; the CAC half — what you spend on ads, sales commission, and onboarding to win one customer — has to be tracked separately from marketing records. Divide the CLTV shown here by that CAC figure; a 3:1 ratio is commonly referenced as a marker of a channel with room to scale, though the useful threshold shifts with your cash conversion cycle and margin structure elsewhere in the business.
What does this calculation leave out?
It assumes flat behavior — the same order size, frequency and margin every year of the lifespan — and does not discount future profit back to present-day dollars or account for referrals a loyal customer might bring in. Real customer cohorts follow a churn curve rather than a fixed lifespan; a more detailed model applies a retention rate period by period instead of one average. This sheet is the quick unit-economics version, not a substitute for cohort-level analysis.
Why use average customer lifespan instead of a churn rate?
Lifespan in years and churn rate describe the same retention from two angles: 1 divided by the annual churn rate approximates the lifespan for a simple model, so a 25% annual churn rate implies roughly a 4-year average lifespan. This sheet asks for lifespan directly because that is what most billing or CRM exports report already; invert a churn percentage first if that is the only figure on hand.
Does this work for subscription billing as well as one-off purchases?
Yes, with one substitution: set Purchases per year to the billing cadence (12 for monthly) and Average order value to the recurring charge, so the frequency term reflects billing cycles rather than discrete purchase decisions. The same multiplication then returns the gross profit expected from one subscriber across their average tenure.
References
- U.S. Small Business Administration — Grow Your Business guide
- U.S. Small Business Administration — Plan Your Business guide
Read this first: This instrument shows arithmetic, not advice. Real offers add fees, taxes and terms that vary by lender and place — verify the figures against your actual paperwork before deciding anything.