HTML5 banner specs: Google Ads, CM360, DV360 and IAB

An HTML5 banner is a zip with one HTML file and the assets it uses. Google Ads takes up to 600 KB and 40 files, Campaign Manager 360 up to 10 MB and 100 files, and DV360 up to 100 files with no size limit of its own. All three read the click-through from a clickTag variable (Google Ads also takes a Google Web Designer exit) and the size from an ad.size meta tag.

Last checked 28 September 2026 against the platforms' own pages · Every figure links to its source

Placement	Shape	File	Length
Google Ads: HTML5	20 fixed sizes	zip up to 600 KB, 40 files	animation 30 s max
Campaign Manager 360: HTML5	any size	zip up to 10 MB, 100 files	no limit set
Display & Video 360: HTML5	any size	zip, 100 files	no limit set
IAB standard: Display banners	12 fixed sizes	GIF/JPG/PNG up to 150 KB; zip, 100 files	animation 15 s max

How do Google Ads, CM360 and DV360 compare?

Rule	Google Ads	CM360	DV360
Zip weight	600 KB	10 MB	no limit set
Files in the zip	up to 40	up to 100	up to 100
Click-through	clickTag or Google Web Designer exit	clickTag	clickTag
ad.size meta tag	required	recommended	recommended
Files from other servers	only Google Fonts and Google-hosted libraries	check with the ad server	check with the ad server
Zip file name	n/a	n/a	under 50 characters
Animation	stops within 30 s	not set	not set

Publishers buying direct usually add their own limits on top; IAB guidance is below. Sources: Google Ads Help: uploaded display ad specs, Campaign Manager 360 Help: prepare HTML5 assets, Display & Video 360 Help: HTML5 creatives.

What is a clickTag and how do I add one?

A clickTag is a JavaScript variable that holds the landing page URL. The ad server replaces its value with its own tracked click URL when it serves the banner, so clicks are counted and the trafficker can change the destination without touching the creative. The banner opens whatever the variable holds when it is clicked.

<meta name="ad.size" content="width=300,height=250">
<script>
  var clickTag = "https://www.example.com";
</script>

<a href="javascript:window.open(window.clickTag)">
  <div id="ad">...</div>
</a>

This is the pattern Campaign Manager 360 and DV360 document. A hard-coded link (window.open('https://...')) still clicks through, but the ad server cannot track it, and CM360 warns about it on upload. Keep the clickTag readable: CM360 asks for it not to be minified. Sources: Campaign Manager 360 Help: prepare HTML5 assets, Display & Video 360 Help: HTML5 creatives.

Why does Google Ads reject an HTML5 zip?

It is over 600 KB or holds more than 40 files.
The HTML has no <!DOCTYPE html> or no ad.size meta tag.
It loads files from other servers. Only Google Fonts and Google-hosted libraries are allowed.
It was built in Google Web Designer for an environment other than Google Ads. Studio creatives, which use the Enabler, do not run in Google Ads.
It uses local storage, or is expandable.
HTML5 upload is only available to eligible Google Ads accounts: open more than 90 days, more than $9,000 lifetime spend and a good policy history.

Source: Google Ads Help: uploaded display ad specs. Google's display sizes and image rules are on the Google Ads specs page.

What does Campaign Manager 360 reject?

Zips over 10 MB or with more than 100 files.
Code that uses local storage, session storage, indexedDB or openDatabase.
A zip inside the zip, or a % sign in any file name.
Files the HTML does not reference, and a backup image packed inside the zip (upload it separately).

CM360 calls the ad.size tag optional but "the best way to be sure your creative renders at the right dimensions", so Gatecheck asks you to review a zip without it rather than failing it. Source: Campaign Manager 360 Help: prepare HTML5 assets.

What about DV360 and IAB?

DV360 takes up to 100 files and sets no size limit of its own, but the zip's file name must be shorter than 50 characters including .zip, or the upload fails. It asks for the same things as CM360: no zips inside the zip, no unused files, no browser storage and no backup image in the zip.

IAB guidance is what publishers buying direct tend to start from. Animation must stop within 15 seconds including loops. IAB sets file weight by unit size (for example 50 KB initial load for 320 × 50 and 150 KB for 300 × 250). Gatecheck applies 150 KB to every size, the common publisher limit. IAB limits an ad to ten file requests during initial load. The 100-file cap is Gatecheck’s default for publisher zips. Source: IAB New Standard Ad Unit Portfolio.

What Gatecheck cannot check in a zip

Gatecheck reads the zip and its code; it does not play the banner. So it cannot time the animation (it reminds you to check the limit), render the creative in each browser, or test third-party trackers and ad tags. Those need a live preview in the ad server.

Full specs

Every rule Gatecheck checks for these placements, with its source.

Google Ads: HTML5

HTML5 display ads uploaded to Google Ads

Sizes	200×200, 240×400, 250×250, 250×360, 300×250, 336×280, 580×400, 120×600, 160×600, 300×600, 300×1050, 468×60, 728×90, 930×180, 970×90, 970×250, 980×120, 300×50, 320×50, 320×100
Zip weight	up to 600 KB
Files in zip	up to 40
Allowed types	html, htm, css, js, gif, png, jpg, jpeg, svg
Click-through	clickTag or Google Web Designer exit
ad.size meta	required

The limit is 600 KB, not the 150 KB many guides still quote (150 KB applies to image ads).
HTML5 upload is only available to eligible Google Ads accounts: open more than 90 days, more than $9,000 lifetime spend and a good policy history.
Animation must stop within 30 seconds.

Source: Google Ads Help: uploaded display ad specs

Campaign Manager 360: HTML5

HTML5 display creatives trafficked in CM360

Zip weight	up to 10 MB
Files in zip	up to 100
Allowed types	html, htm, js, css, jpg, jpeg, gif, png, json, xml, svg, eot, otf, ttf, woff, woff2
Click-through	clickTag variable
ad.size meta	recommended

Upload the backup image separately in CM360, not inside the zip.
The ad.size meta tag is optional in CM360 but it is the surest way to get the right size, so Gatecheck asks you to review a zip without it.
No local storage or session storage, no zips inside the zip, no % in file names.

Source: Campaign Manager 360 Help: prepare HTML5 assets

Display & Video 360: HTML5

HTML5 creatives uploaded to DV360

Zip weight	no limit set
Files in zip	up to 100
Allowed types	html, htm, css, js, jpg, jpeg, gif, png, svg, dfont, eot, otf, ttf, woff, woff2
Click-through	clickTag variable
ad.size meta	recommended

DV360 sets no zip size limit, but publishers do: keep the zip as small as you can.
The zip file name must be shorter than 50 characters, including .zip.

Source: Display & Video 360 Help: HTML5 creatives

IAB standard: Display banners

IAB standard sizes for publisher direct deals

Sizes	300×250, 728×90, 160×600, 300×600, 320×50, 320×100, 970×250, 970×90, 300×1050, 468×60, 336×280, 120×600
Image formats	GIF, JPG, PNG
Image weight	up to 150 KB
Animation	stops within 15 s
Zip weight	no limit set
Initial load	up to 150 KB
Files in zip	up to 100
Allowed types	html, htm, css, js, gif, png, jpg, jpeg, svg, json, woff, woff2, ttf, otf
Click-through	clickTag variable

Animation must not run longer than 15 seconds, including loops.
IAB sets file weight by unit size (for example 50 KB initial load for 320 × 50 and 150 KB for 300 × 250). Gatecheck applies 150 KB to every size, the common publisher limit.
IAB limits an ad to ten file requests during initial load. The 100-file cap is Gatecheck’s default for publisher zips.
Publishers often add their own limits, such as a loop count; add their sheet as a custom spec.

Source: IAB New Standard Ad Unit Portfolio; SizeIM: creative trafficking checklistsecondary

What Gatecheck checks

Drop a file into the checker and it is read in your browser and tested against these placements and the other 20 in the library:

Exact pixel size against every size the placement accepts, including 2× retina files sent by mistake
Image format and file weight, CMYK and wide-gamut colour profiles, EXIF rotation and transparency
GIF and animated PNG timing: total run time including loops, and frame rate
HTML5 zips: weight, file count, file types, clickTag, ad.size, files loaded from other servers and ad-server specific rules

Check an HTML5 zip before the trafficker does

Checking one file at a time is free, with every check. Pro checks a whole campaign against a delivery plan and exports the report. Nothing is uploaded.

Open the checker See a sample campaign

Gatecheck is not affiliated with Google or the IAB. Specs come from their public help pages and, where marked secondary, from industry guides. Every source is linked on this page and was last checked on 28 September 2026.