What is reach?
Reach is the number of unique people, or households or devices, who saw an ad at least once during a set period. It counts each person once, however often they were exposed. Reach can be shown as an absolute number, like 400,000 people, or as a share of a target audience, like 40% of adults in a market.
It is the core metric for awareness campaigns, where the goal is to get a message in front of as many of the right people as possible.
How reach is calculated
Reach is closely linked to impressions and frequency:
Impressions = total number of times the ad was shown.
Reach = unique people who saw it at least once.
Average frequency = impressions / reach.
For example, if a campaign delivers 1,000,000 impressions to 250,000 unique people, reach is 250,000 and average frequency is 4. If the target audience is 1,000,000 people, the campaign reached 25% of it.
In digital advertising, platforms estimate unique reach using user IDs, logins and modeling, since one person may use several devices and browsers. That is why reported reach is always an estimate, and why platforms with strong logged-in or cross-device data tend to report it more reliably. Reach also cannot simply be added up across platforms, because the same person may be counted in each one.
When several channels run together, planners look at deduplicated reach across all of them and at incremental reach: the new people a channel adds that the others did not reach. This is a common way to judge whether adding CTV or online video to a plan is worth it. Planners also use effective reach, the number of people who saw the ad at least a set number of times, such as three, when one exposure is not enough.
Why reach matters
Awareness campaigns depend on getting the message to enough of the right people. Reach tells you how much of your audience the campaign actually touched. As reach grows, each extra point usually costs more, because the easiest people to reach are covered first.
Planning: reach and frequency forecasts help size budgets before launch.
Efficiency: cost per thousand people reached shows whether spend is going to new people or to repeat views.
Balance: pairing reach goals with frequency caps avoids both underexposure and ad fatigue.
Measurement: reach gives context to results like brand lift, which depend on enough people seeing the ads.
Reach vs impressions
Impressions count every ad view, including repeats. Reach counts people. A campaign with 2 million impressions could reach 1 million people twice each or 100,000 people 20 times each, and those are very different outcomes. Looking only at impressions hides that difference, which is why reach and frequency should always be read together.
Reach with AdGeeks
AdGeeks plans reach-focused campaigns on DV360, Amazon DSP and Adform, using each platform's reach forecasting and unique reach reporting where available. Our traders balance channels like video, display and CTV, set frequency caps, and report on unique reach and frequency, not just impressions.
