What Do GRP and TRP Stand For and What Do They Mean?

Today’s out-of-home advertising is data-driven. Measuring OOH performance is not exactly like measuring online or TV, but in some cases, the metrics are the same. For example, GRP and TRP are familiar to TV advertisers, but they also apply to out-of-home. What can they tell you?

GRP = Gross Rating Points

A gross rating point represents 1% of the total in-market audience impressions you can reach with your ad. We say “in-market” to mean those who live within the designated market area, rather than others who may randomly enter or pass through the area.

In a sense, gross rating points represent the big picture. 

If your ad is displayed one time to 100% of the in-market population – one impression per person — that amounts to 100 GRPs. Of course, in reality it’s more complicated than that because not everyone will see your displayed ad, and some people will see it more than once.

Here’s how that works:

• If 100% of the population is exposed to your ad once, that would be 100 GRPs, as noted above.
• But if 50% of the population sees your ad two times, that would also be 100 GRPs.
• If 75% see your ad three times, that's 225 GRPs.

So gross rating points are a function of both reach and frequency. GRPs can give you a good idea how many total impressions your OOH ad(s) may make. They can be measured for mobile OOH as well as static placements.

TRP = Target Rating Points

A target rating point is more definitive. It represents 1% of your specific target audience within the in-market population who are reached by your ad.

What’s the effective difference?

Sometimes you want your ad to reach everybody – or at least as broad an audience as possible. However, if you’re aiming for a more limited group of targets, TRPs give you a more accurate estimate of the total effective (relevant) impressions your ad may make.

Let’s say your target audience makes up only 35% of the overall market population. If your ad is displayed to the total possible audience one time, that would give you 100 GRPs but 35 TRPs.

Reach vs. Frequency

Marketing obviously depends on exposing your audience to your ads. But success depends not only on how many people see it, but how often. Impressions are not enough — you need lasting impressions.

It’s good to aim for impactful, memorable content, but marketers learned a long time ago that repetition is critical. Frequency is crucial to emblazon your brand indelibly on your target’s mind or keep reminding targets of your offer until they take action.

So you must find a balance between reach and frequency, and that depends on your goals.

Reach is your primary concern if your brand is already recognizable and:

• You are introducing a new product or service
• You’re advertising a short-term special – a big sale, or an upcoming event, for example

Frequency is your primary goal if you are:

• Introducing your brand (as a start-up or to a new market)
• Working to build trust (which comes in part from familiarity)
• Facing tough competition for your target audience

OOH offers both versatility and range

Thanks to expanded measurement capabilities, you no longer have to rely on guesswork or anecdotal “evidence” to plan your OOH campaign or know if it is achieving your marketing goals. You can use metrics such as GRP and TRPs along with other data to accurately plan your placements and scheduling to deliver the right content to the optimal audience with effective frequency.