X Ad Image Size: Card Dimensions, Ratios and File Limits
An X ad image used in a card must be at least 800 pixels wide and 3MB or less, according to X's Ads API documentation. Website and App Download cards accept 1:1 and 1.91:1 images, while Poll, Conversation and Direct Message cards accept 1.91:1 only. Supported formats are .bmp, .jpeg and .png.
Checked October 2026. Sources are listed at the end of the page.
X does not ask for one fixed pixel size for card images. It sets a minimum width, a maximum file size and a short list of allowed shapes, and the allowed shapes depend on the card you choose. That makes the safest approach simple: pick the card first, pick a ratio it accepts, then export a file that is wide enough and small enough. The table below collects the rules from X's developer documentation, and the steps after it walk through making an image that passes them.
| Where the image is used | Rule from X | What it means for you |
|---|---|---|
| Any ad card image | 3MB or less, at least 800px wide | Export at 800 pixels wide or more and check the file size before upload. |
| Website card | 1:1 and 1.91:1 | Use a square or a wide landscape image. |
| Image App Download card | 1:1 and 1.91:1 | Same two shapes as the Website card. |
| Poll card | 1.91:1 | Wide landscape only. |
| Image Conversation card | 1.91:1 | Wide landscape only. |
| Image Direct Message card | 1.91:1 | Wide landscape only. |
| Card image formats | .bmp, .jpeg and .png | JPEG or PNG are the common choices. |
| Video Website card video | 16:9 and 1:1 | Make the poster image or thumbnail match the video shape you pick. |
| Promoted video poster image | png or jpg, no aspect ratio or size requirements | X fits the poster to the video player, so match the video shape to avoid odd framing. |
| Images in a regular post (API) | JPG, PNG, GIF, WEBP; 5 MB or less, animated GIF 15 MB or less | This is the post media limit, not the card limit. Card images are stricter at 3MB. |
| Media per post | Up to 4 photos, 1 GIF or 1 video | A post can carry several photos, a card carries one image. |
X Ad Image Size: Card Dimensions, Ratios and File Limits
Choose the card type first
Decide whether the ad is a Website card, an App Download card, a Poll, a Conversation card or a Direct Message card. The allowed shapes differ: Website and App Download cards take 1:1 or 1.91:1, while Poll, Conversation and Direct Message cards take 1.91:1 only. If you might reuse one image across several card types, 1.91:1 is the shape all five accept.
Set the canvas to an allowed ratio and at least 800 pixels wide
X sets a minimum width of 800 pixels, not an exact size. A wide canvas such as 1200 x 628 pixels gives a 1.91:1 image above the minimum, and 1200 x 1200 pixels gives a 1:1 square. These are the two outputs of the free X Image Resizer linked below. Work from the original photo or design file, not a screenshot, so the width is real.
Keep the message clear in a wide frame
A 1.91:1 image is short and wide, so tall subjects and stacked text get cramped. Place the product or face near the centre, keep any headline short and leave the post copy to carry the detail. Post copy has its own limit of 280 weighted characters, and each link counts as 23 characters.
Export as JPEG or PNG and check the file size
Save the image as .jpeg or .png and confirm it is 3MB or less. A large PNG with photo content can go over the limit, so try JPEG if the file is too big. Reopen the exported file and check its width and height, because an editor preset name does not prove the exported dimensions.
Resize an existing image or make a new one
If the picture is ready and only needs the right shape, use the free X Image Resizer to crop or fit it to 1200 x 628 or 1200 x 1200. If you need new artwork, Infinall AI makes images from a prompt on a Studio canvas, can use your saved brand, and offers nine aspect ratios to choose from before you send. Its free Resize tool can then crop or fit the result to a width and height from 64 to 4096 pixels. Check the final export against the table above.
X ad sizes: why there is no single answer
Searches for X ad sizes often expect one magic pixel size. X's documentation instead gives three rules for card images: a minimum width of 800 pixels, a maximum file size of 3MB and an allowed ratio for each card type. Any image that meets all three is accepted, so a 1.91:1 image at 800 pixels wide and one at 1200 pixels wide are both valid.
In practice a larger width within the file limit gives a sharper result on big screens. Pick a width above the minimum, then reduce quality slightly if the file goes over 3MB.
X ad specs for post images versus card images
X has two sets of image rules that are easy to mix up. Images attached to a regular post through the API can be JPG, PNG, GIF or WEBP at 5 MB or less, with animated GIFs up to 15 MB, and a post can carry up to 4 photos. Card images used in ads are stricter: 3MB or less, at least 800px wide, and limited to .bmp, .jpeg and .png.
If you are promoting an existing post with photos, the post media rules apply. If you are building a card with a headline and a destination, use the card rules. When in doubt, prepare the image to the stricter card rules so it works in both places.
X ad dimensions for video posters and thumbnails
Video Website cards accept 16:9 and 1:1 video. X's documentation says poster images for promoted video should be png or jpg, with no aspect ratio or size requirements, and that the poster is adjusted to fit the video player. So the poster does not have a fixed size, but matching it to the video shape keeps the framing predictable: a 16:9 poster for a 16:9 video, a square poster for a square video.
Where Infinall AI fits, and where it does not
Infinall AI helps with the image itself. You describe the picture, pin your brand so the logo, colours and voice carry through, pick one of nine aspect ratios, and the result lands on a Studio canvas. Making images uses credits, and the free plan gives 1,000 credits every month with no card. Resize with Crop or Fit and the Enhance upscaler are free.
Infinall AI does not choose a size for you per X card type, and there is no custom width and height for a new image, so plan to resize after generating. If you only need to reshape a finished image, the free X Image Resizer is quicker. Ad Spy does not search X yet: Meta, Google and LinkedIn are supported, and X is listed as coming soon.
Frequently asked questions
What is the best X ad image size?
X does not fix one size. Card images must be at least 800 pixels wide and 3MB or less, in an allowed ratio. A 1.91:1 image such as 1200 x 628 pixels works for every card type, and a 1:1 image such as 1200 x 1200 pixels works for Website and App Download cards.
What file types does X accept for ad card images?
X's Ads API documentation lists .bmp, .jpeg and .png for card images. JPEG is usually the smallest file for photos, which helps you stay within the 3MB limit.
Can I use a square image in an X ad?
Yes, in Website and App Download cards, which accept 1:1 and 1.91:1. Poll, Image Conversation and Image Direct Message cards accept 1.91:1 only, so a square image will not fit those.
Is the X ad image limit 5 MB or 3MB?
Both numbers exist for different uses. Images attached to a regular post can be up to 5 MB, while images used in ad cards must be 3MB or less. Prepare card images to the 3MB limit.
Can Infinall AI make an image in the right shape for X?
Infinall AI makes images in one of nine aspect ratios from a prompt and your saved brand, using credits. You then use the free Resize tool, or the free X Image Resizer, to crop or fit it to the exact width and height you want.
Sources and checks
Every price, rating and number on this page comes from the source pages below, checked October 2026. Prices and plans change often, so confirm on the vendor's own page before you buy.
- X Ads API: creatives, card image and video specs, checked October 2026
- X API: media best practices, checked October 2026
- X developer docs: counting characters, checked October 2026
- Infinall AI: platforms, file types and sizes, checked October 2026
- Infinall AI: sizes and aspect ratios, checked October 2026
- Infinall AI: upscale and resize an image, checked October 2026
- Infinall AI: Ad Spy, checked October 2026
- Infinall free tool: X Image Resizer, checked October 2026