Important note: This article is about infeed, the placement inside of content or feed.
For mobile fullscreen, we use 640x1280 as the creative size. Then the ad will scale itself to the perfect size to fit the placement. Read more about mobile fullscreen types: mobile interstitial and mobile expandable.
For in-stream ads, we create 8 different sizes to fit the ad for the user's device. Read more about in-stream.
Now, let's talk about the most used infeed placement sizes.
TLDR
The most popular sizes are:
300 x 250 px
300 x 600 px
728 x 90 px
160 x 600 px
120 x 600 px
320 x 100 px
970 x 250 px
320 x 480 px
So, if you create with at least the top 3 or top 5 then you are in good company. For some additional premium locations, you can create a banner called desktop leaderboard (970 x 250) and mobile tower (320 x 480).
Long story
The display media advertisement has a long and complicated history, which has created a myriad of different placement sizes. There are however some guidelines that could help you navigate this landscape.
Shapes and nicknames
As you can deduct from the placement width and height, their ads are in a variety of shapes. That's why most placements have a catchy name that will help people working with ads understand better what's the deal. Here are the above sizes with names:
Inline Rectangle, Medium Rectangle or just Rectangle - 300 x 250 px
Half Page or Tower - 300 x 600 px
Leaderboard - 728 x 90 px
Wide Skyscraper - 160 x 600 px
Skyscraper - 120 x 600 px
Mobile Large Leaderboard - 320 x 100 px
Billboard or Large Leaderboard - 970 x 250 px
Square (Pop-up) - 250 x 250 px
Square - 300 x 300 px
Large Rectangle - 336 x 280 px
Mobile Tower/Interstitial - 320 x 480 px
Large square - 320 x 320 px
Mobile leaderboard - 320 x 50 px
Leaderboard - 728 x 90 px
Mobile - 300 x 50 px
Junior - 300 x 150 px
Large mobile - 320 x 100 px
Super Leaderboard - 970 x 90 px
Mobile, desktop, or both?
As the digital ad landscape evolved more and more different devices came to the market most importantly the prominence of smartphones. Therefore there are some placements for all devices and some are mostly shown to mobile users, some mostly to desktops (usually including also laptops and pads).
Placements for all devices:
(Inline) Rectangle - 300 x 250 px
Square - 250 x 250 px
Square - 300 x 300 px
Large Rectangle - 336 x 280 px
Junior - 300 x 150 px
Mobile-only placements:
Mobile Large Leaderboard - 320 x 100 px
Mobile Tower/Interstitial - 320 x 480 px
Large square - 320 x 320 px
Mobile leaderboard - 320 x 50 px
Mobile - 300 x 50 px
Large mobile - 320 x 100 px
Desktop-only placements:
Leaderboard - 728 x 90 px
Wide Skyscraper - 160 x 600 px
Skyscraper - 120 x 600 px
Billboard or Large Leaderboard - 970 x 250 px
Super Leaderboard - 970 x 90 px