Compute lifetime gross profit and the ratio that gates spending

1. The number, and why it is margin rather than revenue

Lifetime gross profit is the gross profit collected over the lifespan of one customer: every dollar that customer ever hands you, less everything it cost you to deliver what they bought. Other labels are given for the same idea — lifetime value, and customer lifetime value, depending on where you look — and one of the three is sometimes used interchangeably with the others. The instruction attached to the overlap is not to worry about which label you meet.

The gross-profit form is preferred as a matter of wording rather than as a finding: the naming can be confusing, so margin is named outright. Failures below turn on somebody reading revenue where margin was meant.

• What goes into it. Only the costs that rise when you sell one more unit.
• What stays out of it. Rent, administrative staff, utilities, insurance, and the breakages of ordinary trading. Those come out of gross profit later; they are not inside it.

One objection is answered in advance. If a delivery person is paid whether or not the next customer arrives, the cost still belongs inside gross profit, because headcount steps up once a ceiling is reached; take it as a share per customer. It may feel fixed and is not — the stops and starts are chunky rather than absent. The ceiling named there is up to twenty customers per person.

The two figures measure different things: the worked service calculation below runs at ten clients per representative, and twenty is the ceiling before another hire.

2. Step one — gross profit on a single sale

Gross profit is price less the cost of the goods or the service delivered. It is not net profit, which is what survives after every other bill.

Case	Price	Cost to deliver	Gross profit	Gross margin
A manufactured item, shipped	$100	$20	$80	80 percent
A monthly service, one client	$3,000	$600	$2,400	80 percent
A subscription item	$15	$5	$10	Two-thirds
Prepared meals	$10	$9	$1	10 percent

The service row: one account representative costs $6,000 a month and carries ten clients, so $600 of delivery cost falls on each. Each pays $3,000, leaving $2,400, which against $3,000 is eighty percent — run assuming no other cost of delivering the service, an assumption stated rather than hidden. Do this for everything you sell: you may be surprised which products earn least for the time they take.

Gross profit and gross margin are the same measurement in different units. Gross profit is the absolute amount; gross margin is that amount as a percentage of the price.

Flag: the move between the two is stated wrongly. The rule as worded makes gross margin the gross profit multiplied by one hundred percent, which returns the gross profit unchanged. The worked rows above divide the gross profit by the price first, and that is the operation every figure on this page actually uses. The reading carried here is the one the surrounding arithmetic supports. This page does not settle which reading is right.

Flag: a label in the service calculation contradicts its own figure. A line reading revenue per client carries $30,000, while the clients in the same calculation pay $3,000 each. Thirty thousand is ten clients times three thousand — revenue per representative, not per client. The $2,400 result depends on the per-client figure being three thousand, and that is what is carried.

3. The eighty percent rule of thumb, with its scope

A rule of thumb is attached to the service case and its scope is written into it: for a service business, local or national, you want at least an eighty percent gross margin. The reason given is that it is very unlikely you will scale a service business unless you sit at eighty or above. At that margin, something costing you a hundred dollars to deliver has to sell for five hundred.

The rule is stated for service businesses. It is not offered as a figure for manufactured goods, and no margin floor is given for those.

An objection is answered inside the rule. Eighty percent may sound impossible, and it is met with a single correction. It is not net: rent, fixed administration, insurance, utilities, breakages and the advertising spend all still come out of it. A business at eighty percent gross might be running a thirty percent net margin.

4. Step two — how many times a customer buys, or how fast they leave

Routes are given, and which one applies depends on whether what you sell recurs.

Route one, transactional. Export the whole customer history, sort by number of transactions, and average that column. The worked average is four transactions.

Route two, recurring. Work from churn instead. Churn is the share of customers lost between one period and the next. A hundred customers at the start of last month, ninety-five of those hundred still there this month, five lost, five divided by a hundred: five percent.

The correction attached to churn is the part people get wrong. New customers signed during the period do not touch it. You could sign nobody or a thousand and the churn is still five percent, because the same five of the original hundred left.

The estimate is declared as an estimate. Customers arrive, leave and return, so the average is always approximate, and it drifts upward as a business ages.

5. Step three — put the two together

Business shape	Operation	Worked
Transactional	Gross profit × transactions per customer	$80 × 4
Recurring	Gross profit ÷ churn	$2,400 ÷ 5 percent = $48,000

Flag: the transactional product is printed wrong. Eighty dollars multiplied by four transactions is three hundred and twenty dollars. The figure printed beside that multiplication is three hundred and sixty. Both inputs are stated plainly and their product is $320, so $320 is what this page carries. This page does not settle which reading is right.

A second worked chain runs the same way and lands cleanly. An item sells for $15 and costs $5 to deliver, leaving $10 of gross profit. The average customer buys ten times — or stays ten months, which is treated as the same thing for this purpose. Ten times ten dollars is a hundred dollars of lifetime gross profit.

6. The ratio, and the benchmark on it

Divide lifetime gross profit by what the customer cost to acquire. Above one, the customer made you money; below one, they cost you money.

Reading	What it means	What is said about it
Below 1	Customers cost more than they return	You do not have a business that can make money and grow
Around 1	Break-even over a whole lifetime	Not survivable once staff and overhead are counted
3	The stated minimum	At minimum; and at three you are still not in a good position
Above 3	Room to scale	Called a position you can scale hard, from experience rather than from a study
10	A stated target of one owner	Described as one owner's own minimum, not a general rule
20 and above	Some of the best results	Reported, not prescribed

The minimum comes in two phrasings, both kept: the ratio should be over three to one, and you need to be doing at least three to one. Below three is named as a position you should not be in at all. Ideally it is much higher. Worked the other way: a customer returning $300 of gross profit caps what you may pay to win one at a hundred dollars.

Flag: one owner's own lifetime figure is given as different numbers. One reading puts the lifetime return at over thirty-six to one, which is a floor rather than a reading. Another has it moving from four or five to one up to a figure given as thirty-one and up, and then immediately restates that as thirty or forty dollars back on every dollar — which is thirty to one and up, not thirty-one. Nothing procedural hangs on either. This page does not settle which reading is right.

7. The case that fails the ratio

A prepared-meals business is worked through as the failure. It cost $100 to win a customer and the customer paid about $500 across their whole life. On revenue alone that reads as five to one and the team asked to spend more.

The margin is where it breaks, and two margins appear for it.

Reading	Gross margin	Lifetime gross profit	Ratio against $100	First-month gross profit
A	20 percent	$100	1 to 1	$33
B	10 percent	$50	0.5 to 1	Not stated

Flag: the same case carries a second margin. One reading puts the margin at twenty percent and lifetime gross profit at a hundred dollars; another at ten percent and fifty. Price and cost to win are identical in both. Reading A leaves you level over a lifetime; reading B means you never get back what you spent. The business was shut either way, but the readings are not the same number. This page does not settle which reading is right.

The monthly figure under reading A comes off $165 of revenue in a month at twenty percent, which is $33.

Flag: the billing period inside that case is corrected in the same breath. The $165 is first given as weekly across three weeks, then corrected to a monthly figure. Only the monthly reading produces the $33 that the case then uses: three weekly payments inside a thirty-day window would put ninety-nine dollars of margin in the first month, not thirty-three. Monthly is carried here because the $33 depends on it.

Flag: the repair figure is labeled as margin but sized as revenue. The case says the business would have needed $1,500 rather than $500 in lifetime gross profit to work. Against a hundred dollar cost to win, the three-to-one rule asks for $300 of gross profit, not $1,500. Fifteen hundred is what the revenue would have had to reach for twenty percent of it to come to $300. The arithmetic supports $1,500 of lifetime revenue and $300 of lifetime gross profit, and that is the reading carried.

8. A good ratio can still starve you

A customer worth $1,000 of gross profit, won for $100, is ten to one, and that trade is one you should take. It still leaves you short if the thousand dollars arrives as a single payment twelve months later: you are out of pocket on day one and stay out of pocket through the whole delivery. The same shape could equally be put as a ten-year customer paying about a hundred dollars a year — $8.33 a month — and there the first month in which you are ahead is the thirteenth.

Three ways out are named, and only the third is recommended:

1. Spend down your own savings.
2. Spend other people's — debt, or selling part of the business.
3. Make back more than the customer cost inside the first thirty days.

Measuring the delay is SOP 57 — Compute the payback period and shorten it. Grading it against a fixed window belongs to SOP 58.

9. Why this number decides who gets to advertise

Attention on most platforms is sold at auction, so whoever can pay most for a customer takes the customers, and raising what a customer is worth buys the right to bid. The asymmetry named for it: costs bottom out at zero, while what a customer is worth has no ceiling.

The cost side is also narrower than owners expect. Cost to win a customer within one industry runs often fairly similar between competitors, with ranges much tighter than you would think — one estimate is that you might see competitors at $2,500 against $3,500, and that you would rarely see $6,000 unless somebody has only just entered. A separate measurement, taken across many agencies that win small-business owners as customers, found costs within the same industry almost always within one to three times each other — and that measurement carries a condition: it holds where there is no brand doing the work. The gains sit on the value side unless you have a massive brand, which can drive the cost of winning a customer toward almost nothing.

The conclusion drawn from the narrow spread is that the gap between businesses is often not the cost of customers but what each customer is worth.

There are limits on how long that holds. Most platforms use an auction at the time of writing; and the cost of an impression has risen across the last hundred years and will likely keep rising, a new platform being cheap only until the market catches up. If you can make a customer worth more to you than to anyone bidding against you, nobody outbids you.

10. The case behind that conclusion

Two businesses in the same space sold about the same number of units a month, and one made many times the profit of the other. What separated them was how much each made per customer. This page gives no figure for the size of that gap.

11. What this page does not decide for you

• A margin floor for anything but services. The eighty percent rule is written for services.
• How long a customer lifetime runs. No maximum horizon is put on the calculation.
• Which churn period to measure on. The worked churn is month to month.
• What ratio is high enough to stop improving. No ceiling is named.
• How to raise the number. This page gives no figure for how much any single lever moves the ratio.

12. The checklist

Question	The answer
What is measured	Gross profit over a customer's whole lifespan
Other names for it	Lifetime value; customer lifetime value
Step one	Price less cost to deliver, per sale
What is excluded	Rent, administration, utilities, insurance, breakages
Step two, transactional	Average transactions per customer
Step two, recurring	Churn between periods
Does signing new customers change churn	No
Step three, transactional	Gross profit × transactions
Step three, recurring	Gross profit ÷ churn
Service margin rule of thumb	At least 80 percent, service businesses
The ratio	Lifetime gross profit ÷ cost to win a customer
Minimum ratio	Over three to one
Stated target of one owner	Ten to one, not a general rule
What fails the ratio	The meals case: $100 to win; the lifetime return is given as both $100 and $50
Why a good ratio can still fail	The money arrives too late to buy the next customer
How long a lifetime runs	Not established on this page.

13. What this page does not cover

The cost side of the ratio is SOP 56, where the full definition and the three worked computations sit. How fast the money returns is SOP 57, and the thirty-day tests built on it are SOP 58. The eight ways of raising what a customer is worth are SOP 72 — Generate tiers and downsells from the quality vectors, and price itself is SOP 2. Selling more of a thing, a better version of it, or something new is the trio given for raising gross profit without touching price or cost; the quantity and quality levers are on SOP 72, and SOP 40 applies the same three words to advertising. Churn as a diagnostic, rather than as an input to this calculation, is SOP 158 — Diagnose churn by cohort. Commission priced off the cost of winning a customer is SOP 47.

Staffing and delivery scheduling are not covered on this page.