Aspect Ratio Calculator: 9:16 Size in Pixels and More

How do you calculate 9:16 dimensions from a width or height?

Multiply the width by 16 and divide by 9 to get the height; multiply the height by 9 and divide by 16 to get the width. For a 1080-pixel width: 1080 × 16 ÷ 9 = 1920. For a 1920-pixel height: 1920 × 9 ÷ 16 = 1080.

The same rule works for any ratio written as width:height. Multiply the known side by the other side's number and divide by its own. When the answer is not a whole number, round it and accept that the shape is a fraction of a pixel off. For video, round to an even number, because many video encoders need even dimensions; the calculator's "nearest even pixel" option does that.

Is 9:16 the same as 16:9?

Same shape, turned on its side. Ratios are written width first, so 9:16 is portrait (1080 x 1920) and 16:9 is landscape (1920 x 1080, the size YouTube Help lists for 1080p standard video). Both hold the same number of pixels.

The difference matters when one becomes the other. A 16:9 video dropped whole into a 1080 x 1920 frame fills only 607.5 pixels of its height, leaving 68.36% of the frame as bars. Cropping it to fill the frame instead throws away 68.36% of the picture. That is why vertical platforms want footage shot or edited in 9:16 rather than turned from landscape. For the full landscape resolution ladder, see the YouTube video size guide.

Which platforms use 9:16, 4:5, 1:1, 1.91:1 and 3:4?

9:16 is the full-screen vertical ratio: Instagram Story, Instagram Reel, TikTok Video post and YouTube Short. The TikTok video size guide and the YouTube Shorts dimensions guide cover those two in full. 4:5, 1:1, 3:4 and 1.91:1 are Instagram's feed range. In the app: between 1.91:1 and 3:4 (1080 wide, 566 to 1440 tall). Via the publishing API: 4:5 to 1.91:1.

Moving an asset between these shapes is where most cropping mistakes happen. A 1080 x 1350 feed post placed whole in a 1080 x 1920 Story leaves 285 px bars at the top and bottom; filled instead, it loses 228 px off each side. A square post filled into the same frame loses 43.75% of the image. The calculator's preview draws both outcomes for any pair, and a platform preset overlays its safe zone. To produce the crops, use the free Instagram image resizer; for a panorama split across the profile grid, the Instagram grid maker.

What does 1.91:1 mean in pixels?

1.91:1 means the width is 1.91 times the height: a wide, link-preview shape. At 1080 pixels wide the exact height is 565.45; Instagram's help centre gives 1080 x 566 as its widest landscape size.

1.91:1 is itself a rounded number, so the sizes platforms publish for it only come close:

• Instagram Feed photo post : 1080 x 566, which is 1.9081:1
• Facebook Event cover photo : 1920 x 1005, which is 1.9104:1 (widely reported)
• Facebook Link preview image (og:image) : 1200 x 630, which is 1.9048:1
• LinkedIn Link preview image : 1200 x 627, which is 1.9139:1

None of them is exactly 1.91:1. An exact 1.91:1 needs a width that divides by 191, such as 955 x 500 or 1146 x 600. In practice, use the platform's own size: a fraction of a percent never shows in a feed. Meta publishes no event cover size at all; the Facebook event cover photo size guide explains where 1920 x 1005 comes from.

Is 1080 x 1350 the same as 4:5?

Yes, exactly. Divide both sides by 270: 1080 ÷ 270 = 4 and 1350 ÷ 270 = 5, so 1080 x 1350 simplifies to 4:5, a portrait shape with a decimal of 0.8. It is Instagram's portrait feed size and the tallest ratio its publishing API accepts. 1080 x 1440 (3:4) is taller and fills the profile grid tile, but it can only be posted from the Instagram app. The Instagram post size guide covers the grid crop in detail.

Every scheduler publishes through the API, so the API range is the one that applies. Outfeed follows it: Outfeed's publisher sends Instagram a JPEG of at most 8 MB between 4:5 and 1.91:1; a PNG, WebP, GIF, AVIF or TIFF is converted to JPEG, and an image outside the ratio range is padded (never cropped) to the nearest bound before publishing.

From the right size to a scheduled post

Getting the pixels right is step one. Posting the same idea to each platform in its own shape, caption and timing is the rest, and that is what Outfeed AI does. It is a chat-first AI social media manager: you describe the post, it writes it in your brand voice, shows a preview per platform, and schedules and publishes to Instagram, TikTok, LinkedIn, X, Facebook, Threads, YouTube, Pinterest and Bluesky from one conversation.