Reach, Frequency, and Impressions: What Billboard Numbers Actually Mean

By Matt Shepard, owner and operator of the Highway 43 board · September 24, 2026

The three numbers every billboard pitch throws at you

When someone sells you a billboard, three numbers usually come up: impressions, reach, and frequency. Most pitches quote them and move on. Almost nobody stops to explain what they mean or how they fit together. That leaves you nodding along to numbers you can't check.

I run two LED faces on Highway 43 at the Highway 49 junction in Valleyview. I quote billboard impressions every week, so I want you to understand exactly what that word means before you spend a dollar. This is a plain guide to all three numbers, where they come from, and what they say about a board like mine.

Impressions: how many times the ad is likely seen

Impressions are the number of times your ad is likely to be noticed. That is the key word. An impression is not a car and not a person. It is an exposure, and the count includes repeats. If the same person passes the board four times, that is four impressions. Geopath, the audience measurement body in the US, puts it plainly: impressions are the gross count of all the exposures, not the number of people who see the ad.

The number is not raw traffic either. Impression counts are refined using visibility, movement patterns, and demographic data, so they credit people who were actually in a position to notice the ad rather than every vehicle that technically passed. Clear Channel Outdoor describes the same thing in its metrics guide.

On our two faces, more than 6,000 vehicles pass per day, and we count more than 12,000 daily impressions across both faces. That gap between vehicles and impressions is the point of the next section. You can see the full counts on the Highway 43 traffic data page.

Why impressions are not the same as traffic counts

A traffic count is just vehicles on the road. Impressions try to answer a harder question: how many of those passes were a real chance to see the ad. Three things shape the gap.

Direction of travel matters. Our board has two faces. FW faces westbound traffic arriving from Whitecourt and Peace River. FE faces eastbound traffic arriving from Grande Prairie. A driver only sees the face pointed at them, so each face earns its own share of the traffic.

Visibility and dwell time matter just as much. Dwell time is how long a driver is within view of the sign. The longer that window, the more likely the ad gets read. There is a 2025 to 2029 construction speed zone running through our stretch. Slower traffic is not great for a commuter, but it lengthens the time each driver spends looking at the board, which helps the message actually land.

And there is no bypass and no competing boards on that stretch, so the traffic passes the sign instead of routing around it.

Reach: how many different people see it

Reach is how many different people see the ad, counted once each. Where impressions count every exposure including repeats, reach strips out the duplication and counts unique people. It is usually shown as a percentage of a target audience: the share who notice the ad at least once during a campaign.

So impressions and reach answer two different questions. Impressions tell you total exposures. Reach tells you how wide the net is across actual people.

On Highway 43, the audience is a specific mix, not a faceless crowd. Oilfield and industrial crews run repeat routes with good disposable income. Agricultural operators stay loyal to regional brands. Long-haul truckers need fuel, food, lodging, and mechanical work. Local commuters drive to Grande Prairie and back. From May to September, tourists roll through in RVs for hunting and fishing. If you want the fuller picture, I wrote about why the Highway 43 corridor is valuable.

Frequency: how many times the same person sees it

Frequency is the average number of times one person is exposed to the ad. The OAAA defines it as the average number of times an individual notices an OOH message during a set period, and in out of home that period is typically four weeks.

A fixed highway board is built for frequency. The same crews and commuters drive past our faces on a regular schedule, day after day, week after week. Each pass adds another exposure for that same person. A repeat route stacks frequency naturally in a way a one-time placement never can.

Why does that matter? General marketing guidance has long held that people need to see a message several times, often cited as at least three, before it sticks. Treat that as a rule of thumb rather than a promise, and note it is guidance from the wider industry, not a number from my boards. The point stands: repetition builds recall, and a highway board delivers repetition.

How reach and frequency trade off against each other

Here is the tension every budget runs into. The same pool of impressions can be spread wide or stacked deep. Spread it across many locations and you buy reach, more different people seeing it once or twice. Concentrate it on one strong location and you buy frequency, fewer people seeing it more often.

Neither is right or wrong. It depends on what you are trying to do. If you need a lot of people to know a single fact once, lean toward reach. If you need a smaller, defined audience to remember you when they are ready to buy, lean toward frequency.

A repeat-route corridor like Highway 43 tilts toward frequency by its nature. The oilfield crew that drives past FE every morning is going to see your ad again and again. That is worth knowing before you decide what you are buying.

GRP, TRP, and CPM: the numbers built on top

Once you understand reach and frequency, the rest of the jargon is just built on them.

GRP stands for gross rating points. It is reach multiplied by frequency, where one rating point equals 1% of the market population. Reach 40% of the market an average of three times and you have 120 GRPs. Geopath and the OAAA both define it as total in-market impressions expressed as a percentage of the market population. It is a weight measure, not a measure of whether the ad worked.

CPM stands for cost per thousand impressions. The M is the Roman numeral for a thousand. Per the OAAA's standard practices, CPM is calculated on total impressions, and it is the number that lets you compare a board against radio, digital, or anything else on a like-for-like basis. Divide the cost by the impressions in thousands and you get the price of reaching a thousand exposures. You can line that up against real numbers on our packages and pricing page.

Keep the math simple. GRP tells you how heavy the campaign is against a market. CPM tells you what each thousand exposures costs. Both exist so you can compare one option to another.

Who measures these numbers, and who to trust

In Canada, the body behind OOH measurement is COMMB, the Canadian Out-of-Home Marketing and Measurement Bureau. If you are comparing Canadian reach and impression methodology, COMMB is the right citation, not the US bodies. In May 2025 COMMB launched a reach and frequency tool inside its ROADMAP platform that models results down to the individual billboard asset. The company describes it as the result of five years of work and more than a $4 million investment from member media owners.

In the US, the equivalent bodies are the OAAA and Geopath. They are the standard down there, and the definitions in this post lean on their glossaries.

Here is the honest part. I am a small independent operator. I do not run modeled national reach and frequency estimates on my two faces, and I am not going to dress up a guess to sound like one. What I give you is my own traffic data, stated plainly: 6,000 plus vehicles a day, 12,000 plus daily impressions across two faces, in a construction speed zone that slows traffic down. Before you buy from anyone, ask where their numbers come from. If they can't tell you, that is your answer.

What these numbers mean for a Valleyview advertiser

So how should a corridor business read a board's numbers before buying? Start with the three you now understand. Look at impressions for the raw volume of exposures. Look at direction, because FW and FE face different traffic. Look at dwell time, because a slow speed zone means the ad gets read, not just glanced at. Then weigh all of that against the price.

A concrete case. Say you run a fuel stop or a motel in the corridor. Your customers are truckers and crews moving between Grande Prairie, Fox Creek, and Whitecourt, and they make the decision to stop while they are driving. A board they pass on a repeat route, in a zone where traffic slows, builds the frequency that puts your name in their head before they need to pull over. That is a different value than a one-time ad they scroll past once. I broke this down further in the hotels, fuel, and food playbook.

One more practical note. Out of home is bought in weekly cycles, per the OAAA's standard practices, so you plan in weeks and stack them to build frequency over a campaign.

If you want the full numbers behind everything here, download the Highway 43 media kit or ask me for a quote. That is the next step, and it is a plain one.

Sources

Every statistic in this post is checked against a named source before it ships.

Geopath · Impressions are the gross count of all exposures, not the number of people who see the ad.
Clear Channel Outdoor · Impression counts are refined using visibility, movement patterns, and demographic filtering rather than raw traffic.
SRDS · Impressions can include duplicate views; one person seeing an ad four times counts as four impressions.
SRDS · Reach is the number or percent of different people exposed at least once, excluding duplication.
OAAA · Frequency is the average number of times an individual notices an OOH message during a defined period, typically measured over four weeks.
Blip · Common marketing guidance suggests a message needs to be seen several times (often cited as at least three) to build recall.
Geopath · GRP equals reach multiplied by frequency, where one rating point equals 1% of the market population; total in-market impressions expressed as a percentage of market population.
OAAA · CPM (cost per thousand impressions) is calculated using total impressions; OOH campaigns are bought and sold on weekly cycles.
Media in Canada · COMMB launched an enhanced reach and frequency tool within its ROADMAP platform in May 2025, described as five years of work and over a $4 million investment from member media owners.
OOH Today · COMMB is the national not-for-profit body responsible for OOH audience measurement methodology in Canada.
MileAds media kit · MileAds operates two LED faces on Highway 43 at the Hwy 49 junction in Valleyview with 6,000+ vehicles/day and 12,000+ daily impressions, plus a 2025-2029 construction speed zone.