Cost per lead (CPL)
Also known as: CPL, lead cost, cost per inquiry
Cost per lead (CPL) is the marketing spend for a period divided by the number of leads generated in that period, where a lead is a contact that meets an agreed definition.
CPL = marketing spend / number of leadsCost per lead tells marketing what one new contact costs. It stops at the hand-off to sales, which is the difference from customer acquisition cost: CPL counts people who raised a hand, CAC counts people who paid. The arithmetic is trivial. The definition of a lead is where teams disagree, and it decides whether CPL means anything.
Example
A healthcare analytics company has a monthly budget for paid search and LinkedIn of $24,000. The form receives 320 submissions. After removing spam, students and existing customers, 200 remain. Sales accepts 80 of them as a fit.
CPL on raw submissions: $24,000 / 320 = $75. CPL on clean leads: $24,000 / 200 = $120. Cost per sales-accepted lead: $24,000 / 80 = $300.
All three are legitimate. Only the last one predicts revenue. The numbers are illustrative.
How to use it
Write the lead definition into the marketing and sales SLA: which fields, which company size, which sources count. Report CPL per channel and per campaign, then add one column with the share of those leads that sales accepts, the MQL to SQL conversion. A channel with a $60 CPL and 10% acceptance costs more per useful lead than a channel with a $150 CPL and 50% acceptance.
Set a ceiling for CPL from the economics backwards: target CAC multiplied by the lead-to-customer rate.
Common mistakes
- Optimising campaigns toward the lowest CPL. Platforms find the people who fill forms most easily, and lead quality falls.
- Counting duplicates and repeat submissions from the same company as separate leads.
- Changing the lead definition mid-quarter and comparing CPL with the previous period.
- Leaving out agency and content costs, so paid channels look cheaper than organic ones by default.