Google Reach refers to the measurement of the number of people who are exposed to an ad and the frequency at which they are shown the ad. It provides insights into how many unique users have seen an ad and how often they have seen it over a specific time period. Google offers various unique reach and frequency metrics to help advertisers understand the effectiveness of their campaigns across different devices, formats, and networks [[1]](https://support.google.com/goo....gle-ads/answer/24727

Unique reach and frequency metrics include:
- Unique users: The total number of people who were shown an ad.
- Avg. impr. freq. per user: The average number of times an ad was shown to each unique user.
- Avg. impr. freq. per user (7 days): The average number of times an ad was shown to each unique user within a 7-day period.
- Avg. impr. freq. per user (30 days): The average number of times an ad was shown to each unique user within a 30-day period.
- Frequency distribution 1+, 2+, 3+, 4+, 5+, 10+: The distribution of the number of times an ad was shown to unique users, such as the percentage of users who saw the ad once, twice, three times, etc. [[1]](https://support.google.com/goo....gle-ads/answer/24727

To view reach and frequency data, advertisers can add the relevant columns to their statistics table and select a specific time period. It's important to note that reach and frequency metrics may not be immediately available for all campaigns and reporting segments, and there may be a reporting delay of up to 3 days. Additionally, reach estimates are based on statistical models that consider user behavior across different devices and networks, and personally identifiable information is not used [[1]](https://support.google.com/goo....gle-ads/answer/24727

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Learn more:
1. [Measuring reach and frequency - Google Ads Help](https://support.google.com/goo....gle-ads/answer/24727
2. [About ad reach - Google Ads Help](https://support.google.com/goo....gle-ads/answer/17220
3. [Reach Forecasting | Google Ads API | Google for Developers](https://developers.google.com/....google-ads/api/docs/