Standard Display Ad Sizes: 300×250, 728×90 and the Rest

The five sizes that matter most

Google AdSense publishes a guide to ad sizes and names five as top performing. Its notes: the two rectangles tend to have more advertiser inventory available, which can increase earnings; the leaderboard performs well above the main content and on forum sites; and the 300×600 half page is one of the fastest growing sizes by impressions.

The ratios show why one creative does not fit all slots. The medium rectangle is almost square at 1.20:1, the leaderboard is a strip at 8.09:1, and the half page is a column at 1:2.00. A design has to be laid out separately for each shape, not just scaled. The aspect ratio calculator gives the ratio of any size and the missing side when you know one.

The rest of the list

AdSense supports more sizes beyond the top five, plus a few regional sizes for publishers in specific countries. The ones you will meet most often:

Note the names. The IAB calls 160×600 a skyscraper, while AdSense calls 160×600 the wide skyscraper and 120×600 the skyscraper. Quote the pixel size in briefs, not the name.

The IAB standard and file weight

The IAB Tech Lab's New Ad Portfolio lists recommended fixed sizes chosen from a study of which units bring in most revenue. Each has a maximum file weight for the initial load, the files needed for the first display, counted after gzip compression. A further subload, with a limit twice the initial figure, may follow after the page has loaded.

The last column applies the IAB's rule that file weights should be 30 percent less than recommended on connections of 3G speed or slower. Other general requirements in the same document: no more than ten file requests during the initial load, audio muted until the user starts it, and an ad that is clearly distinguishable from the page's own content. A static image ad uses the initial load figure as its limit.

How big to make the artwork

The IAB specification notes that its fixed sizes are calculated on double-density, or 2x, resolution. MDN describes a device pixel ratio of 2 as the expected value for high-density displays: each CSS pixel is drawn with 2×2 physical pixels, so artwork at the slot size is stretched on them. Export at twice the slot:

Twice the size means four times the pixels, so watch the weight: a 600×500 JPG still has to stay under 150 kB. The image resizer produces the 1x and 2x versions from one master, with crop-to-fill for exact slot sizes.

Responsive display ads

Some ad formats are assembled from parts instead of fixed banners. For Google's responsive display ads you upload images, logos and text, and the system fits them to whatever slot is available. Google Ads lists a landscape image of 1200×628 at 1.91:1, with a minimum of 600×314, and a square image of 600×600, with a minimum of 300×300. Logos are 1200×1200 square or 1200×300 at 4:1.

Custom sizes: the IAB weight grid

For a size that is not on the list, the IAB portfolio gives a flexible grid: the file weight allowed depends on how many pixels the ad has, in groups of thousands of pixels. A static image such as a JPG or PNG gets the same limit as the initial load.

The groups only line up with the examples when the pixels are counted at double density, as the specification's footnote says. Counted that way, at four times the slot's area:

A 728×90 at 2x is 262 thousand pixels and falls in the 180 to 300 group; a 300×250 at 300 sits at the bottom of the 300 to 500 group. One example does not fit: the IAB places 970×250 in the 700 to 900 group, but at 2x it is 970 thousand pixels. Its own fixed size table gives it 250 kB, the same figure, so the limit is clear even if the grouping is loose. To place a custom size, work out its pixels at 2x and read off the group.

What a slot earns

CPM is the price or revenue per thousand impressions. Revenue is impressions divided by 1,000 times the CPM. With an assumed CPM of $2.50, a slot shown 120,000 times a month earns $300.00. Your real CPM per size and placement is in the ad network's reports. The CPM calculator works out any one of CPM, cost and impressions from the other two, and the marketing metrics cheat sheet shows how CPM connects to clicks and conversions.

Checklist for a banner set

• Start with 300×250, 728×90 and 320×50 or 320×100; add 300×600 and 970×250 if the placements exist.
• Lay out each shape separately; a square design does not fit an 8:1 strip.
• Export at 2x, then check the weight against the slot's limit.
• Make the ad visibly different from the page, with a border if the background matches.
• Name files with the pixel size, such as spring-300x250.jpg.

Frequently asked questions

Sources

• Google AdSense Help: Guide to ad sizes (top performing sizes 300×250, 336×280, 728×90, 300×600, 320×100; other supported sizes; notes on inventory and placement)
• IAB Tech Lab: New Ad Portfolio, Fixed Size Ad Specifications, 2017 (fixed sizes, maximum initial and subload weights in kB, gzip counting, ten file requests, 30 percent less for slow connections, sizes calculated at double density)
• MDN Web Docs: Window.devicePixelRatio (ratio of physical pixels to CSS pixels; 2 expected for HiDPI displays)
• Google Ads Help: Responsive display ads specs (landscape 1.91:1 at 1200×628, minimum 600×314; square 600×600, minimum 300×300; logo sizes)

Written by Tobias. Updated October 30, 2026.