1. Multiply Traffic count of Advertising Unit X Days that unit is in campaign ( typically 30 days )
2. Divide by 1000
3. Divide monthly cost of unit or unit of time you are measuring by 1000
Example
Traffic count on unit: 10,000 cars per day
Campaign length: 30 days
Unit cost per 30 days: $400.00 net
10,000 x 30 = 300,000
300,000 divided by 1000 = 300
$400 divided by 300 = $1.33
CPM _= $1.33
