CPL and CPA are both cost metrics, but they measure fundamentally different things. Conflating them is one of the most common mistakes in B2B marketing reporting.
Definitions
Cost Per Lead (CPL) = marketing spend ÷ number of leads generated A "lead" is typically defined as a contact who has expressed interest (form fill, demo request, trial signup). Leads have not yet generated revenue.
Cost Per Acquisition (CPA) = marketing spend ÷ number of customers acquired An "acquisition" is a paying customer. CPA accounts for your lead-to-customer conversion rate.
The relationship
CPA = CPL ÷ lead-to-customer conversion rate
Example: CPL of $200, 10% close rate → CPA = $200 / 10% = $2,000
When each matters
CPL is the right metric when: - You want to compare channel efficiency at the top of funnel - Your sales team handles all qualification and closing - Marketing's KPI is "qualified leads delivered to sales"
CPA is the right metric when: - Marketing owns the full funnel including activation - You run direct-response campaigns (e.g. paid social → trial signup → conversion) - You want to compare against LTV for payback period
The danger of optimising for CPL only
A channel with a low CPL but poor lead quality can have a worse CPA than a channel with a high CPL and strong intent signals. Always segment by lead quality (e.g. ICP score, job title, company size) before drawing CPL conclusions.
Use the cost per lead calculator to compute CPL and max allowable CPL from your marketing spend and LTV.