Display Ad Creative Technical Specs Guide

There is no single technical spec for display ad creative; every platform sets its own limits. The Google Ads uploaded display ads specifications (Opens in a new tab) list a 150 KB maximum for GIF, JPG and PNG ads and a 600 KB limit for HTML5 ads, with no more than 40 files in the ZIP. Display & Video 360 caps the total of all creative files a browser downloads at 5 MB per ad and says publishers may require less. Chrome removes an ad that uses more than 4 MB of network bandwidth when the user has not interacted with it. If you design or buy banners, working to the strictest limit that applies is the safest way to avoid rejection.

A spec that serves two readers

For a publisher, a spec protects page speed and the reader's experience. For an advertiser, it prevents rejection, late launches and ads that a browser removes. When the spec is known before the design starts, the designer works inside the limit. When it arrives after delivery, the revision pushes the launch date.

Example scenario: A gift shop prepares banners for a holiday campaign in three sizes. The designer delivers animated files at full resolution, the publisher rejects them for weight and the launch slips by a week. With the spec in hand from the start, the first delivery would have been the right weight. For the size and placement table, see banner ad space sizes and placements; that table is not repeated here.

Tracing each limit to its source

Knowing the source of a limit shows which ones can be negotiated. Google Ads and Display & Video 360 are platform rules. The Chrome page describes browser behavior, and the browser, not the platform, applies it. The IAB Tech Lab LEAN page is an industry framework and gives no file size limit.

Table: limits by source

These limits depend on versions and dates. Google and Chrome pages can change, so check the current pages before delivery. Display & Video 360 says publishers may require less than its maximum.

The four LEAN principles

The IAB Tech Lab LEAN page (Opens in a new tab) expands the acronym as Encryption (HTTPS), Allowing Choice, Non-invasive ads and Lightweight ads. Allowing Choice covers AdChoices and the Transparency & Consent Framework. Non-invasive ads ties to the Coalition for Better Ads. Lightweight ads is described as one of the most critical principles for a better user experience.

The page also says IAB Tech Lab has stopped work on the LEAN Scoring and LEAN Seal initiatives, so LEAN is no longer an active program, and that its principles still apply. It says lightweight ads have not seen the required level of adoption and points to the IAB New Ad Portfolio guidance.

Table: LEAN principles and what they mean for a spec

Encrypted delivery and HTTPS

The LEAN page counts HTTPS among the principles well received and adopted widely. The Google Ads image ad page and the Display & Video 360 HTML5 page do not list HTTPS or SSL as a separate requirement, so you cannot cite those two pages for an HTTPS rule. At the principle level look to LEAN, and at the delivery level look to the publisher's spec.

Practical suggestion: load every resource in the ad package, whether image, font or script, over HTTPS. An ad that triggers mixed content warnings can cause trouble on a publisher's page. Add an HTTPS line to your delivery checklist.

Static and animated image ads

The Google Ads page lists GIF, JPG and PNG as accepted formats for animated and non-animated image ads, with a 150 KB maximum.

Animated GIF: three constraints

• Animation length must be 30 seconds or shorter.
• Animations can loop, but they must stop after 30 seconds.
• Animated GIF ads must be slower than 5 FPS.

These rules limit both weight and distraction. Fewer frames mean a smaller file and less fluid motion. Practical suggestion: tell one message in three or four scenes and hold the call to action on the last frame.

Choosing between JPG and PNG

Practical suggestion: start with JPG for photographic ads and PNG for flat color and sharp edges, then test both against the 150 KB limit. The page does not say which of the two is better; the file weight result decides.

Deciding between GIF and HTML5

Practical suggestion: choose the format from the motion you need, then check it against its own limit. A short sequence of a few scenes fits an animated GIF within 150 KB. Motion that needs interaction, a click tag or the permitted libraries calls for HTML5, which has its own 600 KB limit on Google Ads and a 5 MB total download cap on Display & Video 360.

Example scenario: the gift shop wants a banner that shows three mug designs in turn. Three still scenes fit a GIF, so the shop skips HTML5 and avoids the clickTag setup and the file count rules.

HTML5 packaging rules

According to the Google Ads page, HTML5 ads must be 600 KB or smaller, a ZIP can hold no more than 40 files, and all code and assets must be referenced with a relative path to resources inside the ZIP. External references are allowed only for Google Fonts and the Google-hosted CreateJS, Greensock and jQuery libraries.

The Display & Video 360 HTML5 creative guidelines (Opens in a new tab) use a different yardstick. The total file size of all creative files downloaded by a person's browser is capped at 5 MB per ad, and publishers may require less. An HTML5 .zip can include up to 100 files. Ads can animate for no longer than 30 seconds. A single ad may use up to 25 cookies and 100 HTTP calls.

Table: HTML5 rules on two platforms

How clickTag works

The Display & Video 360 page says HTML5 display ads must use click tags to send users to a landing page. Do not run a code minifier on the click tag, and the landing page must open in a new tab or window. A package that ignores this cannot have its clicks measured.

Where Chrome draws the heavy ad line

The Chrome heavy ads intervention page (Opens in a new tab) lists three limits: the ad uses more than four megabytes of network bandwidth, uses the main thread for more than 15 seconds in any 30-second window, or uses the main thread for more than 60 seconds total. Resources used by descendant iframes count against the limits. Once a user clicks or taps the ad, the limits no longer apply.

An ad that crosses a limit is unloaded and replaced by a gray box with an Ad removed message. The page notes that the CPU interventions are far more likely to trigger on lower-powered devices than on high-end development machines. A separate article covers thresholds, what you see when an ad is removed and ways to cut weight; here only the effect on the spec matters.

Sound and video rules

The Display & Video 360 page says ads that autoplay audio are prohibited, and ads can autoplay video as long as the audio is muted. The Google Ads image ad page states no audio rule. Video ad serving standards are outside this topic.

Motion limits and WCAG

The WCAG 2.2 Pause, Stop, Hide success criterion (Opens in a new tab) (Level A) asks for a mechanism to pause, stop or hide any moving, blinking or scrolling information that starts automatically, lasts more than five seconds and is presented in parallel with other content, unless the movement is essential to an activity. The page explains that five seconds is long enough to get attention and short enough that a user can wait out the distraction.

The WCAG 2.2 Three Flashes success criterion (Opens in a new tab) (Level A) says pages must not contain anything that flashes more than three times in any one second, unless the flash stays under the general and red flash thresholds.

Table: motion rules

Practical suggestion: merge these four rules into one checklist item. A short animation that plays once and ends inside five seconds does not trigger the pause requirement, but any motion beyond that needs a control. For design detail, see banner ad design tips.

Interactive formats and SafeFrame

The IAB Tech Lab SafeFrame page (Opens in a new tab) presents SafeFrame as a web ad framework for rich ad interactions in web pages and apps. For SafeFrame 2.0 it names security as the first priority and says in-frame measurement is no longer needed. The page also says that calling expand() simply expands the ad to the maximum size allowed.

A team building an interactive ad should ask the publisher whether it uses SafeFrame or another container, because the container shapes how the ad expands and communicates with the page.

Setting up a weight budget

Knowing the limit is not enough; you also decide how much each asset may use. Practical suggestion: manage file weight as a budget table and list every asset.

Table: sample budget lines for a 600 KB HTML5 package

Measurement method

Do not measure weight by the ZIP size alone. Display & Video 360 caps what a browser downloads, so resources the ad fetches while running count as well, and the Chrome page says descendant iframe resources count against its limits. Measure in two steps.

1. Compare the package size with the platform's file limit.
2. Run the ad in a browser and read the total downloaded data in the network panel with the cache disabled, which the Chrome page recommends for consistent results.
3. Repeat on a lower-powered device profile, because the Chrome page says CPU interventions are far more likely to trigger there.

One budget for each size

Each banner size in a campaign is its own file with its own limit. A wide leaderboard and a small mobile banner carry different artwork, so their weights differ. Record the measured weight and the share of the limit used for each size in the handoff table, so you see early which size is close to the edge.

Keeping revision notes

Each revision can change the weight. A small copy edit that adds a font weight grows the package. Put the version number, the change and the measured weight in the handoff table, and put the version in the file name so an old file does not stay live by mistake.

Proof to hand the publisher

Send more than the file: add the weight measurement, the animation length and the list of external resources. Those three items shorten the publisher's review and lower the chance of rejection. A yes or no next to each checklist line is enough.

Link to page speed

Ad weight affects more than acceptance; it also affects the publisher's page speed. For the publisher side of that balance, see ads and Core Web Vitals: the publisher balance.

When two limits disagree

When sources set different limits, apply the following order. Practical suggestion: adopt the strictest limit that applies to each ad type.

1. The publisher's written spec comes first when one exists.
2. If a platform limit is stricter than the publisher's, the platform limit applies.
3. Browser thresholds are an extra ceiling in every case; Chrome can remove an ad even when a platform accepted it.
4. Accessibility rules are not limits but extra conditions every ad must meet.

Example scenario: The gift shop's HTML5 banner looks loadable under the platform rule, but the publisher asks for a lower total download. By the second rule the package is lightened to the publisher's limit. Because the Chrome threshold applies anyway, compressing images and loading video only on user request enter the design from the start.

Writing the publisher spec

A publisher that sells ad space should publish its limits on one page. Practical suggestion: write the source and the ad type next to every limit.

Table: publisher spec template

For the broader brief and delivery process, see ad space creative brief and file handoff checklist; the page here only collects technical spec lines.

How a breach becomes visible

Decision table: stage, symptom and rule

Checklist for the designer handoff

• Is the file within the strictest weight limit among the publisher and the platform?
• Was every size measured separately?
• Does the animation stay within 30 seconds and stop after the loop?
• Is the GIF frame rate slower than 5 FPS?
• Is there a pause control for motion longer than five seconds?
• Is flashing avoided?
• Does the HTML5 package use relative paths and only the permitted external libraries?
• Is the click tag set up correctly and left unminified?
• Is autoplay audio absent?
• Are all resources loaded over HTTPS?

Template for the delivery note

Practical suggestion: attach the same short note to every delivery.

• Creative code, size and version
• Package size next to the platform limit
• Total data downloaded, with the cache disabled and a lower-powered profile
• Animation length and the second it stops
• List of external resources and HTTPS status
• Click tag setup and landing page address
• What changed since the previous version

Example scenario: when the gift shop sends version two, only two lines change: a font weight was removed and the measured download was rewritten. The publisher reviews those two lines and skips the rest.

Mix-ups to clear up

150 KB versus 600 KB

150 KB is the image ad limit. 600 KB is the HTML5 package limit. They belong to different ad types.

600 KB versus 5 MB

600 KB is the Google Ads HTML5 file limit. 5 MB is the Display & Video 360 ceiling on everything a browser downloads. Because the yardsticks differ, one package can pass on one platform and fail on the other.

Acceptance by a platform versus Chrome

A platform accepting an ad does not mean Chrome will keep it. The Chrome rule applies in the browser when the user has not interacted with the ad.

Taking LEAN for a size cap

The LEAN page gives no file size limit. It states a lightweight principle and refers to other standards.

Equating ZIP size with download size

The ZIP size leaves out what the ad fetches while it runs. Display & Video 360 caps what a browser downloads, and Chrome counts sub-frame resources, so a small ZIP is no guarantee.

Mistaking WCAG items for weight caps

The WCAG criteria govern motion and flashing, not file weight. An ad inside every weight limit may still need a pause control for motion longer than five seconds, so keep the two checklists apart.

Frequently Asked Questions

When does Chrome remove an ad?

According to the Chrome page, ads the user has not interacted with that use more than 4 MB of network bandwidth, more than 15 seconds of main thread in any 30-second window, or more than 60 seconds of main thread in total.

How large may a banner file be?

According to the Google Ads page, uploaded image ads are limited to 150 KB and HTML5 ads must be 600 KB or smaller. Display & Video 360 caps the total of all files a browser downloads at 5 MB per ad, and publishers may require less.

Is autoplaying sound allowed?

The Display & Video 360 page says ads that autoplay audio are prohibited, while ads can autoplay video as long as the audio is muted.

For how long may an animated GIF ad play?

The Google Ads page says the animation must be 30 seconds or shorter, may loop but must stop after 30 seconds, and must be slower than 5 FPS.

Does an animated banner need a pause control?

The WCAG 2.2 Pause, Stop, Hide criterion asks for a pause, stop or hide mechanism for moving, blinking or scrolling information that starts automatically, lasts more than five seconds and sits alongside other content, with an exception where the movement is essential.

Is HTTPS required for ads?

The IAB Tech Lab LEAN page lists Encryption (HTTPS) among its principles. The Google Ads image ad page and the Display & Video 360 HTML5 page do not list it as a separate requirement; check the publisher's spec.

Conclusion

The technical spec for display creative is a combination of platform, publisher and browser rules. Google Ads lists 150 KB for image ads and 600 KB with 40 files for HTML5, Display & Video 360 lists 5 MB total download and 100 files, and Chrome lists 4 MB and CPU thresholds for ads without user interaction. LEAN gathers lightweight, HTTPS, choice and non-invasive principles, and WCAG adds the pause control and the flash limit.

Work to the strictest limit that applies, share the handoff checklist with the publisher and measure every size on its own. To manage creative delivery and the launch plan together, you can explore ad spaces.