Glossary /
Viewable Impression
Efficiency & cost
Viewable Impression
An impression that actually had a chance to be seen—measured against the MRC standard, and priced as vCPM.
Attribution & Measurement
Unit Economics
Data Governance & Nomenclature
Creative & Delivery
Audiences & Targeting
Mobile & Privacy
A viewable impression is an ad impression that met the MRC viewability standard—at least 50% of the ad's pixels in view for one second for display, or two seconds for video. vCPM is the cost per thousand viewable impressions.
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What is Viewable Impression?
A served impression and a viewable impression are not the same thing. An ad can be served below the fold, in a background tab, or scrolled past instantly—counted, but never actually in view. Viewability filters for impressions that had a real chance to be seen. The industry baseline is the MRC standard: at least 50% of the ad's pixels visible on screen for a minimum of one second for display ads, or two seconds for video. vCPM—cost per thousand viewable impressions—lets you price and compare media on impressions that cleared that bar rather than raw served volume. The catch is that "viewable" is measured slightly differently by each platform and measurement vendor. The MRC threshold is common ground, but what counts as a measurable impression, how in-app and cross-frame cases are handled, and which vendor verifies it all vary. Two systems can report different viewability rates for the same buy.
Viewable Impression formula
vCPM = (Spend ÷ Viewable Impressions) × 1,000
vCPM = (Spend ÷ Viewable Impressions) × 1,000. You divide total spend by the number of impressions that met the viewability standard, then multiply by 1,000 to express it as a cost per thousand viewable impressions—so you're paying against ads that could actually be seen, not raw served volume.
Worked example
A display campaign measured to the MRC viewability standard.
Ad Spend
$3,000
Viewable Impressions
500,000
vCPM
$6.00
($3,000 ÷ 500,000) × 1,000 = $6.00
Viewability (50% of pixels, 1s display / 2s video) is measured differently by each platform and vendor, so vCPM is not strictly comparable.
Viewable Impression formula
vCPM = (Spend ÷ Viewable Impressions) × 1,000
vCPM = (Spend ÷ Viewable Impressions) × 1,000. You divide total spend by the number of impressions that met the viewability standard, then multiply by 1,000 to express it as a cost per thousand viewable impressions—so you're paying against ads that could actually be seen, not raw served volume.
Worked example
A display campaign measured to the MRC viewability standard.
Ad Spend
$3,000
Viewable Impressions
500,000
vCPM
$6.00
($3,000 ÷ 500,000) × 1,000 = $6.00
Viewability (50% of pixels, 1s display / 2s video) is measured differently by each platform and vendor, so vCPM is not strictly comparable.
How Viewable Impression differs across ad platforms
Ad servers (Campaign Manager 360)
Report viewability against the MRC standard but depend on their own measurable-impression logic—some impressions can't be measured for viewability at all.
DSPs and exchanges
Apply the MRC threshold but handle in-app, cross-frame, and video differently, so reported viewability rates shift by environment.
Third-party verification vendors
Verify viewability independently and often report a different rate than the buying platform for the same impressions.
Common Viewable Impression misconceptions
A viewable impression means a user actually looked at the ad.
It only means the ad met a visibility threshold—50% of pixels in view for the minimum time. It's about the opportunity to be seen, not proof of attention.
Every platform measures viewability the same way because there's an MRC standard.
The 50%/1s/2s threshold is shared, but measurable-impression rules, in-app handling, and the verifying vendor differ—so reported viewability rates vary across systems.
Frequently Asked Questions
What is Viewable Impression in simple terms?
A viewable impression is an ad that actually appeared on screen long enough to have a chance of being seen—not just one that was served somewhere on the page. The standard bar is at least half the ad in view for a second (two seconds for video).
How is Viewable Impression calculated?
Why does Viewable Impression differ across ad platforms?
How does Clarisights report on Viewable Impression?
Attribution & Measurement
Unit Economics
Data Governance & Nomenclature
Creative & Delivery
Audiences & Targeting
Mobile & Privacy
A viewable impression is an ad impression that met the MRC viewability standard—at least 50% of the ad's pixels in view for one second for display, or two seconds for video. vCPM is the cost per thousand viewable impressions.
?
?
What is Viewable Impression?
A served impression and a viewable impression are not the same thing. An ad can be served below the fold, in a background tab, or scrolled past instantly—counted, but never actually in view. Viewability filters for impressions that had a real chance to be seen. The industry baseline is the MRC standard: at least 50% of the ad's pixels visible on screen for a minimum of one second for display ads, or two seconds for video. vCPM—cost per thousand viewable impressions—lets you price and compare media on impressions that cleared that bar rather than raw served volume. The catch is that "viewable" is measured slightly differently by each platform and measurement vendor. The MRC threshold is common ground, but what counts as a measurable impression, how in-app and cross-frame cases are handled, and which vendor verifies it all vary. Two systems can report different viewability rates for the same buy.
Viewable Impression formula
vCPM = (Spend ÷ Viewable Impressions) × 1,000
vCPM = (Spend ÷ Viewable Impressions) × 1,000. You divide total spend by the number of impressions that met the viewability standard, then multiply by 1,000 to express it as a cost per thousand viewable impressions—so you're paying against ads that could actually be seen, not raw served volume.
Worked example
A display campaign measured to the MRC viewability standard.
Ad Spend
$3,000
Viewable Impressions
500,000
vCPM
$6.00
($3,000 ÷ 500,000) × 1,000 = $6.00
Viewability (50% of pixels, 1s display / 2s video) is measured differently by each platform and vendor, so vCPM is not strictly comparable.
How Viewable Impression differs across ad platforms
Ad servers (Campaign Manager 360)
Report viewability against the MRC standard but depend on their own measurable-impression logic—some impressions can't be measured for viewability at all.
DSPs and exchanges
Apply the MRC threshold but handle in-app, cross-frame, and video differently, so reported viewability rates shift by environment.
Third-party verification vendors
Verify viewability independently and often report a different rate than the buying platform for the same impressions.
Common Viewable Impression misconceptions
A viewable impression means a user actually looked at the ad.
It only means the ad met a visibility threshold—50% of pixels in view for the minimum time. It's about the opportunity to be seen, not proof of attention.
Every platform measures viewability the same way because there's an MRC standard.
The 50%/1s/2s threshold is shared, but measurable-impression rules, in-app handling, and the verifying vendor differ—so reported viewability rates vary across systems.
Frequently Asked Questions
What is Viewable Impression in simple terms?
A viewable impression is an ad that actually appeared on screen long enough to have a chance of being seen—not just one that was served somewhere on the page. The standard bar is at least half the ad in view for a second (two seconds for video).
How is Viewable Impression calculated?
Why does Viewable Impression differ across ad platforms?
How does Clarisights report on Viewable Impression?
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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