Most guides to banner ad sizes list a dozen formats and stop. That is fine if you buy ads. If you sell space on your own site, the question is different: which sizes will you accept, and where do they go?
A sponsor needs an answer before they brief a designer. Send them the wrong size and you either squash it into a slot it was not built for, or you ask them to start again.
This is the website banner ad sizes guide for the person selling the slots.
The sizes WB Ad Manager knows about
The plugin names a set of standard formats, so you can pick one instead of typing pixel values.
| Format | Size (px) |
|---|---|
| Leaderboard | 728 x 90 |
| Large leaderboard | 970 x 90 |
| Banner | 468 x 60 |
| Mobile banner | 320 x 50 |
| Mobile large banner | 320 x 100 |
| Medium rectangle | 300 x 250 |
| Large rectangle | 336 x 280 |
| Skyscraper | 160 x 600 |
| Wide skyscraper (half-page) | 300 x 600 |
| Square | 250 x 250 |
There are two more choices. Responsive fills any slot, and Custom size lets you enter your own width and height. If a custom size matches a standard one exactly, the plugin treats it as that format.
How to read a size name
A banner size is written as width by height, in pixels. A leaderboard at 728 x 90 is 728 pixels wide and 90 high. The names are conventions the advertising industry settled on, so a sponsor’s designer will often know them: medium rectangle, skyscraper and the rest.
Two cautions help. First, the pixel size is the size on the page, so the image you upload should match it. The image ad prints a plain image tag, and the plugin does not resize or convert the file for you. Second, a size is not a promise about how many readers see it. A sidebar skyscraper on a page where the sidebar drops below the content on a phone may reach far fewer people than its place on the desktop suggests.
Which size goes where
Each placement has a list of sizes it is designed for. The ad editor uses those lists to match a fixed-size ad to compatible placements, which helps keep a 728-pixel banner out of a narrow sidebar.
| Placement | Sizes it is designed for |
|---|---|
| Header | Leaderboard, large leaderboard, banner |
| Footer | Leaderboard |
| Before or after content | Leaderboard, medium rectangle, large rectangle |
| After a paragraph | Medium rectangle, large rectangle |
| Sidebar widget | Medium rectangle, skyscraper, wide skyscraper, square |
| Before or after the archive list | Leaderboard |
| Sticky bar | Mobile banner, mobile large banner |
| Popup | Medium rectangle, large rectangle |
| Comments | Medium rectangle |
| bbPress forums | Leaderboard, medium rectangle |
| BuddyPress activity feed | Medium rectangle |
Responsive ads suit every placement. The shortcode placement is for responsive ads only, because the container is yours to control.
Format matching is guidance, not a lock
The table above shows the sizes each placement is designed for. The ad editor uses that list when you choose a fixed size, so it can point you toward matching placements.
At display time the check is not enforced by default. If you tick a placement that does not suit the size, the page can still show the ad. That means the plugin will not stop a 728 x 90 banner going into a narrow sidebar, so the check is yours to make. Preview the live page at desktop and phone width after you publish, and move the ad if it is cut off or overflows.
Mobile banner ad sizes
Phones need their own sizes. A 728 x 90 leaderboard is wider than most phone screens, so it will not fit a mobile layout.
The plugin names two mobile formats: the mobile banner (320 x 50) and the mobile large banner (320 x 100). The sticky bar placement is designed for exactly these two, which is why a desktop creative sent for that slot will not work. If you sell the sticky bar, say on your rate card that it takes a 320 x 50 or 320 x 100 file.
A medium rectangle (300 x 250) also fits on a phone, since it is narrower than the screen, and it can sit in the content or after a paragraph. For everything else, a responsive ad adapts to the slot, which is the easiest route when a sponsor cannot supply a separate mobile file. Whatever you accept, open the page at phone width before you publish and check that nothing is cut off.
A sample rate card layout
This is an example of how the sizes might be listed for sponsors. The slot names and sizes come from the tables above, and every other detail is yours to set.
| Slot | Size | Where it appears |
|---|---|---|
| Header banner | 728 x 90 | Top of every page |
| In-content | 300 x 250 | After a chosen paragraph |
| Sidebar | 300 x 250 | Sidebar widget area |
| Mobile bar | 320 x 50 | Sticky bar on phones |
Beside the table, add the booking length, the file formats you accept and the date by which the creative must arrive. One page with this on it saves you most of the back and forth.
Notice that two rows use the same size. A sponsor can build one 300 x 250 creative and run it in both, which is why that size is the easiest to sell.
Choosing sizes to sell
Do not offer every size. A short list is easier to sell and easier to design for.
Think about it from the sponsor’s side. A medium rectangle (300 x 250) is listed for more placements than any other fixed size: in the content, after a paragraph, in the sidebar, in popups and in comments. A sponsor who builds one creative at that size can run it in most of your slots.
A leaderboard (728 x 90) suits the top and bottom of a page and the archive lists. It is wide, so it works on desktop layouts and not on narrow ones.
The sticky bar on mobile is designed for the two mobile banners. If you sell that slot, say so on your rate card, because a desktop creative will not fit.
A sensible starting menu for a small site is two sizes: one medium rectangle for in-content and sidebar slots, and one leaderboard for the header. Add others when sponsors ask.
Fixed size or responsive
In the ad editor, the Sizing box has two options.
- Responsive fills any slot. The plugin’s own note says it suits AdSense auto and fluid HTML.
- Fixed size has a known width and height, and matches only compatible slots.
Under Fixed size there is a Format dropdown, which includes an option to auto-detect from the image. We suggest you pick the format yourself when you create an ad. It takes one click, and it means you know which placements the ad will match before you publish.
Image ads usually have a known size, so Fixed size fits sponsor banners. Use Responsive for network tags such as AdSense, where the network chooses the size.
File formats and weight
Sponsors will send whatever their designer exports, so say what you accept. The common choices are JPG, PNG and GIF for images. The plugin does not compress or convert them, and it does not add lazy loading or modern formats for you. A heavy file therefore goes to your readers as it arrives.
Set a file size ceiling on your spec sheet and hold to it. If a creative is much heavier than the ceiling, ask for a lighter export instead of accepting it, because every reader pays for the weight on every page that shows the ad.
Animated creatives need a word of their own. Decide whether you accept them, and for how long. A quiet static image beside a long article is usually kinder to readers than a loop beside the text.
What to send a sponsor
Put these on your “Advertise with us” page or in your booking email. Sponsors should never have to ask.
- The exact pixel sizes for each slot you sell, such as 300 x 250 for the sidebar and 728 x 90 for the header.
- A file size cap you are comfortable with. Heavy creatives slow your pages, and your readers feel it.
- A destination URL, which the plugin tracks clicks against.
- Alt text for the image, since image ads have an alt text field.
- Start and end dates, which you will set on the ad.
- A mobile version, if the slot shows on small screens and your layout needs one.
Keep the list short. A sponsor who gets a clear spec sheet tends to send a creative that works the first time.
When the wrong size arrives
It happens to every publisher. A sponsor sends a 600 x 200 image for a 300 x 250 slot. There are three honest options.
- Ask for the right file. This is the usual answer, and it takes one email.
- Use a custom size. If the slot can take an odd size, enter the sponsor’s width and height under Custom size. Check that the placement and the page layout can hold it.
- Offer a different slot. Some sizes suit another position better, such as a wide banner in the header.
Do not stretch an image to fit. A stretched banner looks poor and reflects on the sponsor and on your site.
Checking the live page
Before you tell a sponsor their ad is live, check it yourself.
- Open the page in a private window so you see what a reader sees.
- Look at it at desktop width and at phone width.
- Confirm the ad is labelled, and that the link goes to the right place.
- Check that nothing overlaps the text or pushes the first screen down.
- Send the sponsor a screenshot of the live placement.
That screenshot is also your record of what you delivered. Keep it with the booking.
Keeping creatives organised
A sponsor who books for a month, then renews with a new creative for the next season, leaves you with a growing pile of ads. The free plugin lets you tag ads by sponsor, season or format, filter the list by tag and switch a whole group on or off at once.
That is useful when a seasonal campaign ends: tick the group, switch it off in one action, and the slot is free. Pro adds ad folders, which let you browse by advertiser and campaign and pause a whole folder in one click. For a small site, tags are usually enough.
Whichever you use, put the size in the ad name, for example the sponsor, the slot and 300 x 250. When you are scanning a list of forty ads, the size tells you at a glance whether it can replace another.
Sponsors who ask for something unusual
Sooner or later a sponsor asks for a size that is not on your list, or for a takeover of the whole page. You do not have to say yes, and you do not have to say no outright.
For an odd banner size, the Custom size option lets you enter any width and height. Say yes only after you have checked that the placement and the layout can hold it, and tell the sponsor which slot it will live in. For a larger deal, such as several slots for the same sponsor over a month, build each slot as its own ad with its own dates, then tag them together so you can switch the group on and off at once.
A short, repeatable answer works best: here are the sizes we sell, here is the price for each, and anything else is a conversation.
Writing the spec in one paragraph
If you only have time for one paragraph on your “Advertise with us” page, make it a spec. For example: “Sidebar and in-content slots take a 300 x 250 image in JPG, PNG or GIF, under the file size we list. The header takes 728 x 90. On phones the sticky bar takes 320 x 50. Send the file, a destination URL and alt text at least a few days before the start date.” Everything a designer needs is in four sentences.
After the creative arrives
Open WB Ad Manager > Add New Ad, upload the image, set the Sizing and Format, tick the placement, and set the dates. Then check the page at phone width, because a banner that fits a desktop sidebar can look different on a narrow screen.
Our walkthrough on placing your first ad zones covers the placements in more detail. If you are building a rate card around these sizes, how to sell ad space on your website covers pricing and booking. And if you run AdSense in the same slots, AdSense and direct sponsors in the same slot explains how they share it.