Banner Ads: Sizes, Viewability, and Preflight
A banner ad is a display unit on a site or app, usually a fixed or flexible rectangle that links to a destination. It is one format inside display, not a synonym for every image ad.
A banner ad is a rectangular display unit placed on a website or app to promote a brand, product, or service. It usually links to a landing page. It is one display advertising format. Native units, video, and responsive display ads share some buying paths and do not behave like a static 300x250.
Teams still buy banners through ad networks and paid media plans. Read click-through rate next to viewability and destination match, not as the only score. Carousel ads are a different multi-image format, mostly on social placements.
Sizes: fixed slots and flexible standards
IAB’s New Ad Portfolio (Tech Lab page last updated February 7, 2024; IAB.com page last updated February 25, 2025) replaced the old Universal Ad Package as IAB’s creative guideline set. New units are based on aspect ratio and size range, so one design can scale. Many publishers still auction the older fixed slots.
Google Ads uploaded display specifications, accessed September 20, 2026, still list those fixed sizes for image, AMPHTML, and HTML5 uploads. Image ads: GIF, JPG, or PNG, 150 KB. HTML5 and AMPHTML: ZIP 600 KB or smaller. Some sizes are regional.
| Size (pixels) | Google Ads name | Typical use |
|---|---|---|
| 728 x 90 | Leaderboard | Desktop page header |
| 300 x 250 | Inline rectangle | In-content or sidebar |
| 160 x 600 | Wide skyscraper | Sidebar |
| 320 x 50 | Mobile banner | Mobile web header |
| 300 x 600 | Half-page | Larger sidebar |
| 970 x 250 | Billboard | Premium desktop header |
That table combines Google Ads upload eligibility with common publisher slots. Each exchange, app, and direct publisher can accept a different list. Responsive display ads adapt uploaded assets to available Google Display Network slots, while static banners remain fixed.
HTML5 behavior. Google HTML5 ads are a ZIP of local HTML, CSS, JS, and images. Expandable ads are not supported. Access requires account eligibility (Google documents a 90-day account, lifetime spend, and policy-history bar, then an application). If you cannot use HTML5, Google points to AMPHTML or responsive display ads. Animated GIFs must stop by 30 seconds and run slower than 5 FPS.
Viewability, frequency, match, and safety
Google Active View follows MRC viewable-impression rules:
- Display: at least 50% of pixels in view for at least one continuous second. Ads of 242,500 pixels or more may use 30% for one second.
- Video: at least 50% in view while playing for at least two seconds.
- Viewable is not “a person looked at it.” Non-measurable impressions are a third bucket.
Frequency capping belongs in the same plan. Five viewable impressions in a day to the same user or device identifier create a different experience from one viewable impression.
Destination and message match. The smallest size must still show brand, offer, and next step. The landing page must keep that offer. Pair this with landing page experience.
Brand safety. Exchange and network banners inherit placement risk. Use brand safety controls, and do not treat a GDN or open-exchange path as interchangeable with a homepage takeover.
Measurement. Decide whether the contract prices served impressions, viewable impressions, clicks, or conversions. Google Active View separates measurable, non-measurable, viewable, and non-viewable impressions. Read creative CTR alongside measurable and viewable rates so poor visibility is not mistaken for a message problem.
Preflight checklist
- Confirm the buying path and the size or asset list it actually accepts.
- Export the correct dimensions; do not letterbox a 728x90 into a 300x250.
- Stay inside file-weight caps (150 KB images; 600 KB HTML5/AMPHTML ZIP on Google Ads).
- Check contrast, type size, and alt text. Do not put meaning in color alone.
- Stop looping animation at the placement’s limit (30 seconds for Google GIF uploads).
- Match headline, offer, and landing page.
- Set viewability and frequency expectations in the insertion or platform.
- Apply brand-safety and exclusion lists for open inventory.
- QA the click-through, including mobile, and the conversion tag.
- Follow the platform’s HTML5 backup-image rules. Display & Video 360 makes the backup optional and requires it to be uploaded separately from the ZIP.
A banner earns attention through message hierarchy before decoration. If a viewer cannot name the brand, the offer, and the action at the smallest size, do not run another color test on the same weak line.
Video explainer
Marketing Explained published this overview of display advertising types, which includes banner units among other formats.
Video: Marketing Explained, What is Display Advertising & Types of Display Ads.
Frequently Asked Questions
What is a banner ad?
A banner ad is a rectangular display unit on a website or app that promotes a brand, product, or service and usually links to a landing page. Native, video, and responsive asset-based ads are related display formats, not identical inventory.
What are standard banner ad sizes?
Google Ads still accepts many fixed uploaded sizes, including 728x90, 300x250, and 160x600. IAB’s New Ad Portfolio now emphasizes aspect ratio and flexible size ranges rather than only those fixed pixels. Match the placement, and use responsive display ads when the slot can vary.
How do banner ads get bought?
Advertisers buy banners through the Google Display Network, a DSP and exchange path, a network package, or a direct publisher deal. Each path has different size, file, viewability, and brand-safety rules.
What makes a banner ad ready to run?
The size and weight match the placement, the brand and offer are readable at the smallest size, the destination matches the message, contrast and alt text are in place, and viewability and frequency are planned. For HTML5, follow the buying platform’s backup-image rules.
Sources
- IAB Tech Lab, New Ad Portfolio, last updated February 7, 2024, accessed September 20, 2026.
- IAB, New Ad Portfolio, last updated February 25, 2025, accessed September 20, 2026.
- Google Ads Help, Uploaded display ads specifications, accessed September 20, 2026.
- Google Ads Help, About common sizes for responsive display ads, accessed September 20, 2026.
- Google Ads Help, Responsive display ads specs, accessed September 20, 2026.
- Google Ads Help, Understanding viewability and Active View, accessed September 20, 2026.
- Display & Video 360 Help, HTML5 creatives, accessed September 20, 2026.
- MRC Viewable Ad Impression Measurement Guidelines, accessed September 20, 2026.
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