A lead is not worth what your competitor pays for one. It is worth what it converts into, times how often it converts, times what is left after you deliver.
Working that out before you launch is the difference between a campaign you can judge and one you argue about.
The formula
Value per lead = average deal value × gross margin × close rate
Target CPL = value per lead × the share of it you are willing to spend on acquisition
The second line is the part people skip. If you spend the entire value of a lead acquiring it you break even before overhead, so pick a deliberate share — a third and a half are common — and write down why.
A worked example
A commercial cleaning company:
- Average contract value in the first year: $9,000
- Gross margin after labour and materials: 35% → $3,150 of gross profit
- Leads that become customers: 8%
Value per lead: 3,150 × 0.08 = $252.
At a third of that, target CPL is $84. At half, $126. Both are defensible; what is not defensible is discovering after the fact that you have been paying $300.
Notice how violently the close rate moves this. At 4% rather than 8%, value per lead halves to $126 and the same $84 lead goes from comfortable to marginal. Lead quality is not a soft concern here — it is half the equation.
Cost per lead is not cost per acquisition
They get used interchangeably and they are not the same:
- CPL is spend ÷ leads.
- CPA is spend ÷ customers.
- CPA = CPL ÷ close rate.
That $84 lead at an 8% close rate is a $1,050 customer acquisition cost. Against $3,150 of gross profit that is a ratio of about 3:1, which is healthy. Reporting the $84 as though it were the cost of a customer is how a sales pipeline gets described as four times more efficient than it is.
What to do when you do not know your close rate yet
Guess, deliberately and pessimistically, and label it as a guess. Then instrument it: tag the source on every lead so that in ninety days you have a measured rate instead of an assumption. Nearly every business that thinks it has a CPL problem has an attribution problem — the leads are converting, nobody is recording which campaign they came from.
Three inflation traps
Counting form fills as leads. If half of them are bots or wrong numbers, your real CPL is double what the dashboard says. Count qualified leads, and define qualified before you start.
Using revenue instead of gross profit. A $9,000 contract that costs $5,850 to deliver is worth $3,150 to this calculation. Using the $9,000 gives you a target CPL almost three times too generous.
Ignoring the sales cost. If a lead takes two hours of somebody's time to work, that time belongs in the arithmetic.
Do the arithmetic
The target CPL calculator takes deal value, margin and close rate and prints the ceiling. Browser-only, no account.
Then treat the number as a decision rule rather than a report: campaigns above it get fixed or stopped, campaigns below it get more budget. That single rule is most of what disciplined lead-gen looks like.