Definition
Cost per lead is paid media spend divided by the number of leads that spend produced. It is the first-order efficiency metric for any paid channel: how much does one inquiry cost from this source?
The integrity of CPL depends entirely on the denominator. If total leads from all sources — including organic search, referrals, and walk-ins — are divided into paid spend, the resulting number is a blended average that understates what paid channels actually cost. The honest version counts paid-source leads only.
Why it matters
CPL drives budget allocation. A CPL flattered by organic volume sends money to channels that don't deserve it, and the error compounds every cycle the blended number goes unchallenged.
How Pennant treats it
Pennant computes CPL as spend ÷ paid-source leads, per channel and per program, with gross and net spend tracked separately. Organic volume is reported alongside but never enters the cost math.