Cost per lead (CPL)
What is cost per lead (CPL)?
Cost per lead is the advertising spend divided by the number of leads it produced. It is the first honest measure of a campaign, and an incomplete one: a channel with a low cost per lead and a poor close rate is more expensive than it looks, so it is read together with the cost per won customer.
How it is calculated
CPL = advertising spend ÷ number of leads. A campaign that cost €1,200 and brought 80 enquiries has a CPL of €15. What counts as a lead has to be agreed first: a sent form, a call longer than a minute, a quote request, a download in exchange for an email. Mixing them makes the number meaningless.
The leads must also be counted reliably, with conversion tracking on the forms and call tracking for phone calls, or the CPL in the ad platform and the enquiries in the inbox will not match.
Example
A kitchen studio advertises on Facebook with lead ads and on Google with search ads. Facebook brings 150 leads a month for €1,500, a CPL of €10. Google brings 40 leads for €1,200, a CPL of €30. On CPL alone, Facebook looks three times better.
The CRM tells another story. Of the 150 Facebook leads, 6 become orders; of the 40 from Google, 8 do. The cost per order is €250 from Facebook and €150 from Google. The studio moves part of the budget to search and adds one qualifying question to the Facebook form (“When do you plan to install the kitchen?”), which halves the number of leads and doubles the share that buys.
Why it matters for a business
CPL is the first honest measure of a campaign: it shows how much interest the money bought, weeks before the sales do. It is also incomplete, and optimising it alone is a common trap. The cheapest leads often come from forms that are too easy to fill in, audiences that are too broad, or offers that attract people who will never buy.
Read CPL together with the share of leads that become customers, and with the cost per won customer, which needs sales data from a CRM. Lead scoring then helps sales spend its time on the leads most likely to buy.
What to ask
- What exactly do we count as a lead, and is it the same in every channel?
- What share of the leads from each channel become customers?
- What is our cost per won customer by channel, not only per lead?
- Do the leads in the ad platform match the enquiries that actually reached us?
Cost per lead is read together with how many leads become sales. That is how we read it in the Google Ads campaigns we run.