Social media image sizes

Instagram — square post 1080 × 1080, portrait 1080 × 1350, landscape 1080 × 566, story and reel 1080 × 1920. Portrait 4:5 occupies the most feed space.

LinkedIn¹ — post and link share 1200 × 627, square 1200 × 1200, cover banner 1584 × 396, profile photo 400 × 400 minimum, company logo 300 × 300.

Facebook — feed post 1200 × 630, story 1080 × 1920, cover photo 851 × 315, profile 320 × 320.

X² — in-stream image 1600 × 900 (16:9), header 1500 × 500.

Pinterest — 1000 × 1500 (2:3). Pinterest is the one platform where tall genuinely outperforms.

YouTube — thumbnail 1280 × 720, channel art 2560 × 1440 with the safe area in the middle 1546 × 423.

Upload a 12-megapixel photo to Instagram and it has to reduce it to 1080 pixels wide and compress it for delivery. That happens on their servers with their settings, tuned for storage cost rather than for your photograph.

Hand over a file already at the target dimensions and reasonably compressed, and their encoder has very little left to do — so it does less, and what people see stays closer to what you exported.

This is the entire reason correct dimensions matter. It is not that the platform rejects wrong sizes; it is that wrong sizes hand the platform more work, and its work is worse than yours.

Two traps catch people repeatedly.

Cover banners crop differently on mobile. LinkedIn and Facebook both cut the left and right edges on phones. Keep anything important — text, faces, logos — well inside the centre.

Feed previews crop to square. A landscape image may display as a centre-cropped square in some grid views. If the composition falls apart when squared off, it will fall apart in the grid.

When you share a URL rather than an image, the platform does not use anything you chose. It reads the og:image tag from that page, per the Open Graph protocol³.

So if your own articles preview badly, the fix is on your website, not in the post. Make sure each page has an og:image at 1200 × 630, referenced by an absolute URL — a relative path is the single most common cause of a blank preview. Platforms also cache aggressively, so use their debugging tool to force a refresh after changing it.

Every major platform re-encodes uploads to its own specification, which is why a carefully exported image can still look worse than it did on your machine.

You cannot prevent this, but you can avoid making it worse. The failure mode is uploading an already heavily-compressed file: the platform's encoder treats your artefacts as real detail and compresses them again, and the second pass is where visible damage appears.

The counter-intuitive but correct advice: upload at high quality and correct dimensions, and let the platform do its own compression once. A 400 KB image at the right size survives re-encoding far better than a 60 KB one you pre-compressed to be helpful. Generation loss explains why the damage stacks.

For most web work, file size is the thing to manage. On social platforms, dimensions matter more, because getting them wrong triggers cropping you do not control.

Upload something at the wrong aspect ratio and the platform crops to fit — usually from the centre, sometimes with face detection, never with your intent. Text near an edge disappears. A logo in a corner is cut in half.

Two practical rules: keep anything that must survive — text, faces, logos — well inside the centre of the frame, and check the actual rendered result on a phone rather than trusting the desktop upload preview, which frequently crops differently.

A separate problem from upload sizing, and one that generates a lot of confusion: the image shown when someone shares a link to your site is not chosen by the platform's judgement. It is read from meta tags in your page's HTML.

The relevant tags are og:image and, for some platforms, twitter:image. Without them, platforms fall back to guessing — often picking a logo, an advert, or nothing.

The specified image should be around 1200×630, which is the aspect ratio most platforms crop toward. An image at a very different ratio gets cropped, which is why a tall portrait shot makes a poor link preview no matter how good the photograph is.

Two practical notes. Platforms cache these aggressively, so a fix will not appear on already-shared links until their cache expires — most offer a debugging tool that forces a refresh. And the URL must be absolute, including the domain; a relative path silently fails.