How to use it
Tap CPL, Spend or Leads in the equation to pick the unknown, then fill in the other two for the same date range. A lead is whatever your campaign counts as one: a form fill, a demo request, a newsletter sign-up or a call. Use the same definition every time you compare.
Add your lead-to-customer rate to follow the leads through to sales. It is the share of leads that become paying customers, typed as a percentage: 10 means 10%. The calculator then shows how many customers those leads make and the cost per customer. If you don't know the rate yet, the conversion rate calculator works it out from customers and leads.
The formula
CPL = spend ÷ leads
Spend = CPL × leads
Leads = spend ÷ CPL
HubSpot writes it as the cost of lead generation divided by the total number of leads. Mailchimp's guide uses the same division: $500 of ads that bring in 50 leads is a $10 cost per lead.
With a lead-to-customer rate:
Customers = leads × lead-to-customer rate
Cost per customer = CPL ÷ lead-to-customer rate
Worked examples
Finding CPL. A lead-generation campaign cost $2,500 last month and brought in 125 leads. $2,500 ÷ 125 = $20.00 per lead. If 10% of those leads buy, that is 12.5, shown as 13 customers, at $20.00 ÷ 0.10 = $200.00 each.
Mailchimp's example. $5,000 of marketing spend and 125 leads: $5,000 ÷ 125 = $40.00 per lead.
Leads a budget should bring in. You have $3,000 and aim for a CPL of $24. $3,000 ÷ $24 = 125 leads.
Spend a target allows. You want 400 leads at $15 each: $15 × 400 = $6,000.
| Spend | Leads | CPL |
|---|---|---|
| $2,500 | 125 | $20.00 |
| $5,000 | 125 | $40.00 |
| $3,000 | 125 | $24.00 |
| $6,000 | 400 | $15.00 |
CPL, CPA and CAC
All three are spend divided by a count. What changes is the count.
- CPL divides by leads: people who raised a hand but haven't bought.
- CPA (cost per acquisition) divides by conversions, whatever the campaign counts as one. When the conversion is a lead form, CPA and CPL are the same number.
- CAC (customer acquisition cost) divides by new paying customers, and often includes sales costs as well as marketing.
So CPL is usually the earliest and lowest of the three. A cheap lead that never buys is not a bargain, which is why the lead-to-customer rate matters: a $20 lead that converts at 10% costs $200 per customer, while a $40 lead that converts at 25% costs $160. The CAC calculator takes the cost per customer further, with sales costs included.
How this calculator handles your numbers
The sums run on exact fractions, and money is rounded once, at the end, to two decimals, half away from zero. Leads and customers are whole numbers. When a result comes out as a fraction of a lead or customer, it is rounded to the nearest whole one and the exact figure is shown below the answer. Zero leads, or a zero CPL when solving for leads, gets a message instead of a result, because the division has no answer. A lead-to-customer rate must be above 0% and no more than 100%.