The number of people within your campaign's defined target audience that you’re expected to reach. On-target reach is based on age, gender and geographic location of your target audience.
On-target reach is the absolute number of people in your target audience that's being reached by a campaign, while on-target percentage reach is the percentage of a census-based demographic audience that's being reached by your campaign. You can calculate the on-target percentage reach by dividing the on-target demographic reach by the on-target demographic population.
Let’s say that your ad reached a total of five million people in Texas out of an estimated 30 million people who live in Texas. Your on-target percentage reach would be 16.7%.