Glossary /
Reach
Efficiency & cost
Reach
How many distinct people saw your ads — and why you can't just add it up across platforms.
Attribution & Measurement
Unit Economics
Data Governance & Nomenclature
Creative & Delivery
Audiences & Targeting
Mobile & Privacy
Reach is the number of unique users who saw your ad at least once, while Frequency is the average number of times each of them saw it (impressions divided by reach). Together they describe spread versus saturation.
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What is Reach?
Reach counts people, not impressions. If your ad was shown 10,000 times to 4,000 distinct users, your reach is 4,000 and your frequency is 2.5. Reach tells you how wide you went; frequency tells you how hard you hit the same people. The deep problem is deduplication. Each platform only dedupes within its own walled garden. Meta knows how many unique Meta users saw the ad; Google knows its own unique users. Neither knows about the other's. So a person who saw your ad on both YouTube and Instagram is counted once by Google and once by Meta. That means you cannot sum reach across platforms to get total unique people — you'd double-count anyone exposed on more than one. Cross-platform reach is an estimate at best, and only meaningful once you acknowledge the overlap that no single platform can see.
Reach formula
Frequency = Impressions ÷ Reach
Frequency equals total impressions divided by reach, where reach is the count of unique users exposed. Rearranged, impressions = reach × frequency. The limitation is that reach is only deduplicated inside one platform's user graph — there's no shared identity layer across walled gardens to dedupe a person seen on two platforms.
Worked example
A single platform's awareness campaign.
Impressions
1,000,000
Reach (unique users)
250,000
Frequency
4.0
1,000,000 ÷ 250,000 = 4.0
Reach is deduplicated only inside one walled garden — you cannot add Google reach and Meta reach to get true combined reach.
Reach formula
Frequency = Impressions ÷ Reach
Frequency equals total impressions divided by reach, where reach is the count of unique users exposed. Rearranged, impressions = reach × frequency. The limitation is that reach is only deduplicated inside one platform's user graph — there's no shared identity layer across walled gardens to dedupe a person seen on two platforms.
Worked example
A single platform's awareness campaign.
Impressions
1,000,000
Reach (unique users)
250,000
Frequency
4.0
1,000,000 ÷ 250,000 = 4.0
Reach is deduplicated only inside one walled garden — you cannot add Google reach and Meta reach to get true combined reach.
How Reach differs across ad platforms
Meta Ads
Meta dedupes reach across Facebook and Instagram using its logged-in identity graph, which makes its in-platform reach quite reliable. But that dedup stops at Meta's wall — it has no visibility into who also saw your ad on Google or TikTok.
Google Ads
Google reports unique reach across Search, YouTube, and Display using its own signed-in and modeled data. It dedupes within Google's surfaces only, so a user counted here may be the same person Meta also counted — with no way for either to know.
TikTok Ads
TikTok reports reach against its own user base and dedup logic. Like the others, it's a self-contained walled garden, so its unique-user count overlaps with Google's and Meta's whenever the same person is on multiple platforms.
Common Reach misconceptions
You can add up reach from each platform to get total unique people.
No — each platform only dedupes within itself. Summing reach double-counts anyone exposed on more than one platform, inflating your true unique audience. Cross-platform reach is an estimate, not a sum.
Higher reach is always the goal.
Reach without enough frequency rarely drives action, and reach with runaway frequency wastes budget and annoys people. Read reach and frequency together against your campaign objective.
Related Terms
Frequently Asked Questions
What is Reach in simple terms?
Reach is how many different people saw your ad at least once. If your ad showed up 10,000 times but only 4,000 distinct people saw it, your reach is 4,000. Frequency then tells you how many times each of those people saw it on average.
How is Reach calculated?
Why does Reach differ across ad platforms?
How does Clarisights report on Reach?
Attribution & Measurement
Unit Economics
Data Governance & Nomenclature
Creative & Delivery
Audiences & Targeting
Mobile & Privacy
Reach is the number of unique users who saw your ad at least once, while Frequency is the average number of times each of them saw it (impressions divided by reach). Together they describe spread versus saturation.
?
?
What is Reach?
Reach counts people, not impressions. If your ad was shown 10,000 times to 4,000 distinct users, your reach is 4,000 and your frequency is 2.5. Reach tells you how wide you went; frequency tells you how hard you hit the same people. The deep problem is deduplication. Each platform only dedupes within its own walled garden. Meta knows how many unique Meta users saw the ad; Google knows its own unique users. Neither knows about the other's. So a person who saw your ad on both YouTube and Instagram is counted once by Google and once by Meta. That means you cannot sum reach across platforms to get total unique people — you'd double-count anyone exposed on more than one. Cross-platform reach is an estimate at best, and only meaningful once you acknowledge the overlap that no single platform can see.
Reach formula
Frequency = Impressions ÷ Reach
Frequency equals total impressions divided by reach, where reach is the count of unique users exposed. Rearranged, impressions = reach × frequency. The limitation is that reach is only deduplicated inside one platform's user graph — there's no shared identity layer across walled gardens to dedupe a person seen on two platforms.
Worked example
A single platform's awareness campaign.
Impressions
1,000,000
Reach (unique users)
250,000
Frequency
4.0
1,000,000 ÷ 250,000 = 4.0
Reach is deduplicated only inside one walled garden — you cannot add Google reach and Meta reach to get true combined reach.
How Reach differs across ad platforms
Meta Ads
Meta dedupes reach across Facebook and Instagram using its logged-in identity graph, which makes its in-platform reach quite reliable. But that dedup stops at Meta's wall — it has no visibility into who also saw your ad on Google or TikTok.
Google Ads
Google reports unique reach across Search, YouTube, and Display using its own signed-in and modeled data. It dedupes within Google's surfaces only, so a user counted here may be the same person Meta also counted — with no way for either to know.
TikTok Ads
TikTok reports reach against its own user base and dedup logic. Like the others, it's a self-contained walled garden, so its unique-user count overlaps with Google's and Meta's whenever the same person is on multiple platforms.
Common Reach misconceptions
You can add up reach from each platform to get total unique people.
No — each platform only dedupes within itself. Summing reach double-counts anyone exposed on more than one platform, inflating your true unique audience. Cross-platform reach is an estimate, not a sum.
Higher reach is always the goal.
Reach without enough frequency rarely drives action, and reach with runaway frequency wastes budget and annoys people. Read reach and frequency together against your campaign objective.
Frequently Asked Questions
What is Reach in simple terms?
Reach is how many different people saw your ad at least once. If your ad showed up 10,000 times but only 4,000 distinct people saw it, your reach is 4,000. Frequency then tells you how many times each of those people saw it on average.
How is Reach calculated?
Why does Reach differ across ad platforms?
How does Clarisights report on Reach?
See Viewable Impression across every channel in one report
See Viewable Impression across every channel in one report
See viewability and vCPM across every platform—display, video, programmatic— in one normalized report, instead of reconciling vendor numbers by hand.
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