Banner Ad Sizes: The Formats That Perform

A banner that looks great as a 300×600 can become unreadable when it is squeezed into a 320×50 slot on a phone. And a banner in a size no publisher supports simply never shows. Choosing the right banner ad sizes is the unglamorous step that decides whether your display budget is spent at all.

The good news: you do not need dozens of sizes. A handful of standard formats covers most inventory, and responsive ads fill the gaps.

This guide lists the standard sizes from the IAB (the industry body that sets ad specs) and Google’s current image ad specifications, explains file-size limits, and gives you a priority order for designing banners in 2026.

Key Takeaways

• Five sizes cover most display inventory: 300×250, 728×90, 320×50, 300×600 and 160×600.
• Google’s uploaded static display ads in Demand Gen accept JPG, PNG or non-animated GIF up to 150 KB.
• IAB guidelines set file-weight limits per size – 150 KB initial load for the medium rectangle and leaderboard.
• Use responsive display ads alongside fixed banners so Google can fill sizes you did not design.
• Design for the smallest size first; if the message works at 320×50 it will work everywhere.

The standard banner ad sizes

The IAB Tech Lab’s New Ad Portfolio defines fixed-size ad units and their maximum file weights. The figures below come from its fixed-size specification document (© 2017 IAB Technology Laboratory), which remains the reference most publishers build to.

Name	Size (px)	Initial load max	Subload max	Where it appears
Medium rectangle	300×250	150 KB	300 KB	In-content and sidebars, desktop and mobile
Leaderboard	728×90	150 KB	300 KB	Top of page on desktop
Super leaderboard / pushdown	970×90	200 KB	400 KB	Wide desktop headers
Billboard	970×250	250 KB	500 KB	High-impact desktop header
Skyscraper	160×600	150 KB	300 KB	Desktop sidebars
Portrait	300×1050	250 KB	500 KB	Tall desktop sidebars
Smartphone banner	320×50 or 300×50	50 KB	100 KB	Top or bottom of mobile pages and apps
Mobile interstitial	640×1136, 750×1334 or 1080×1920	300 KB	600 KB	Full-screen in apps

“Initial load” is what the ad may download before the page finishes loading; “subload” is extra content loaded afterwards. The IAB also says file weights should be about 30% lower for connections at 3G speed or slower.

“Ad must not exceed ten file requests during initial file load.”

— IAB Tech Lab, IAB New Ad Portfolio: Fixed Size Ad Specifications

Google Ads banner specs in 2026

Google is moving its Display campaigns into Demand Gen, so the current specs for uploaded banners sit in Google’s Demand Gen image specifications. For static uploaded display ads, Google lists:

• Formats: JPG, PNG or GIF (non-animated only)
• Maximum file size: 150 KB
• Up to 20 images per ad
• Recommended sizes: 300×250, 336×280, 728×90, 970×90, 160×600, 300×600 and 320×50

“Animations aren’t supported.”

— Google Ads Help, Image asset specifications for Demand Gen campaigns

Google’s migration notes say HTML5 uploaded ads and third-party ads are planned for Demand Gen in late 2026, so animated HTML5 banners may return – check the help centre before you build them.

Responsive image sizes

Responsive and Demand Gen image ads do not use fixed banner sizes. Instead you upload images in aspect ratios and Google crops and assembles them:

Ratio	Recommended	Minimum	Use
1.91:1 landscape	1200×628	600×314	Most display and Gmail placements
1:1 square	1200×1200	300×300	Feeds, mobile, Discover
4:5 portrait	960×1200	480×600	Mobile feeds
9:16 vertical	1080×1920	600×1067	YouTube Shorts
1:1 logo	1200×1200	128×128	Logo slot (max 150 KB)

Which sizes to design first

If you only have time or budget for a few banners, design in this order:

1. 300×250 medium rectangle – works on desktop and mobile, in-content and sidebar.
2. 320×50 mobile banner – most traffic is on phones; this is the hardest size to design, so do it early.
3. 728×90 leaderboard – standard desktop header slot.
4. 300×600 half page – large, visible, good for product imagery.
5. 160×600 skyscraper – common sidebar unit.
6. 336×280 and 970×90 – optional extras that widen reach.

Then add a responsive display ad with landscape, square and portrait images so the system can fill everything else. See our display advertising guide for how these formats fit into a campaign.

How to design banners that work at every size (step by step)

1. Write one message. A single benefit plus a call to action. Our ad copywriting guide helps here.
2. Start at 320×50. If the headline does not fit there, shorten it.
3. Use a consistent layout system. Logo, headline, image and button in the same order across sizes.
4. Make the button look like a button. High contrast, clear verb (“Get a quote”, “Shop now”).
5. Keep text legible. Avoid tiny type; check on a real phone screen.
6. Add a border if the background is white, so the ad does not blend into the page.
7. Compress files. Stay under 150 KB for Google uploads; the same principles as image compression for web pages apply.
8. Name files by size and version (e.g. offer-a_300x250.png) so testing and reporting are easy.
9. Match the landing page. The banner promise must match the page; see PPC landing pages.

Banner design checklist

• Brand or logo visible in every size
• One headline, under about six words for small sizes
• Clear call to action
• Readable on mobile without zooming
• File size within network limits
• No misleading “fake button” or system-warning designs (these break ad policies)
• Landing page loads fast and repeats the offer

Common mistakes

• Shrinking a desktop design for mobile. Text becomes unreadable at 320×50; redesign instead.
• Too much copy. Banners are glanced at, not read.
• Oversized files. Heavy files are rejected or slow the page; stay within limits.
• Uploading animated GIFs where they are not supported. Check the format rules first.
• Only fixed sizes. Without responsive assets you miss inventory.
• No testing. Run at least two creative variants and judge on conversions, not just click-through rate.

Related Guides

• Programmatic Advertising Explained
• How to Set a PPC Budget
• PPC KPIs: Metrics Every Advertiser Should Track

Frequently Asked Questions

What is the most common banner ad size?

The 300×250 medium rectangle is one of the most widely supported sizes. It is in the IAB fixed-size portfolio and on Google’s list of recommended uploaded display ad sizes, and fits both desktop and mobile layouts.

What is the file size limit for Google display banners?

Google’s specs for uploaded static display ads in Demand Gen list a maximum of 150 KB per image, in JPG, PNG or non-animated GIF format.

Can I upload animated GIF banners to Google Ads?

Not for static uploaded display ads in Demand Gen – Google states that animations are not supported in that format. Google says HTML5 uploaded ads are coming to Demand Gen in late 2026.

Do I need every banner size?

No. Start with a core set – 300×250, 728×90, 320×50, 300×600 and 160×600 – and use responsive display ads to cover the rest.

What size is a mobile banner?

The standard smartphone banner is 320×50 (300×50 is also in the IAB portfolio). The 300×250 rectangle also performs well on mobile pages.

Conclusion

Banner sizes are a solved problem once you know the standards: build the core five, keep files light, and pair them with responsive images. The real gains come from clear messaging and steady testing. If you would like help planning and producing display creative and running the campaigns, see our PPC management services or request a quote. For tracking results, our conversion tracking guide is the place to start.

References

1. IAB New Ad Portfolio: Fixed Size Ad Specifications – IAB Tech Lab
2. Image asset specifications for Demand Gen campaigns – Google Ads Help
3. Google Display Ads campaigns have a new home in Demand Gen – Google Ads Help
4. About responsive display ads – Google Ads Help
5. Banner Ad Sizes: Choosing the Right Size – Semrush Blog