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OTS and LTS: Core Metrics for Measuring Outdoor Advertising Performance
- 2026.02.20
With the advancement of digital technology and data analytics, the way we measure the effectiveness of Out-of-Home (OOH) advertising has become increasingly sophisticated. At the center of this evolution are two key metrics—OTS (Opportunity To See) and LTS (Likely To See). These indicators help advertisers distinguish between potential reach and actual exposure, leading to more realistic performance assessments.
1. What is OTS?
OTS (Opportunity To See) refers to the number of people who have the opportunity to see an ad.
It includes everyone within the area where the advertisement could potentially be visible.
For instance, if a large outdoor billboard is placed near Euljiro 1-ga Station in Seoul, everyone who passes through or visits the nearby area is counted in the OTS population. OTS does not indicate whether the person actually saw the ad—it measures the potential exposure range instead.
2. What is LTS?
LTS (Likely To See) refers to the number of people who are likely to actually see the ad.
It is a more refined measure than OTS, focusing on individuals who are in a position where the advertisement is visibly in their line of sight. This metric considers factors like distance, viewing angle, lighting, and visual obstructions.
Using the same Euljiro 1-ga example, only people located within the area where the billboard is clearly visible—without being blocked or out of view—would be included in the LTS population.
3. Key Differences Between OTS and LTS
Category |
OTS (Opportunity To See) |
LTS (Likely To See) |
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Definition |
People who have the opportunity to see the ad |
People who are likely to actually see the ad |
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Range |
Broad area where the ad could reach |
Limited area where the ad is visible |
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Example |
Overall foot traffic around the station |
People positioned where the billboard is visible |
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Use |
Measures coverage (potential reach) |
Measures real impact (actual exposure) |
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4. Why They Matter
Using both OTS and LTS allows advertisers to analyze the efficiency of outdoor campaigns more accurately.
Objective performance measurement: Avoids overestimating ad impact by using raw foot traffic data alone.
Precise targeting: With big data, AI, and location-based analytics, OTS and LTS can be calculated with high accuracy for targeted audience segmentation.
Optimized ad spending: Advertisers can focus budgets on placements that ensure higher visibility and stronger results.
5. Conclusion
OTS represents the people who could see the ad, while LTS captures the people who likely did.
Together, they form the foundation for a data-driven evaluation of outdoor advertising performance, enabling smarter and more strategic media planning.