What Size Should Social Media Post Images Be? A Straight Answer

You have written the caption. The announcement goes out in twenty minutes. You open the image you made, drop it into Instagram, and the top of your headline is gone — sliced off by a crop you did not ask for. So you go looking for the right dimensions, and the internet hands you a spreadsheet with forty numbers on it, half of them out of date.

Here is the thing nobody says plainly enough: you do not need forty numbers. You need four shapes. Once you know which shape goes where, the pixel counts take care of themselves.

Aspect ratio matters more than pixel count

Every platform resizes your image. What no platform will do is change its shape without cutting something off. That is why aspect ratio — the relationship between width and height — is the thing to get right, and raw resolution is a distant second.

Upload a wide banner to a feed that expects something tall and the platform crops the sides, or shrinks it into a letterboxed strip that nobody stops scrolling for. Upload a tall graphic as a link preview and the top and bottom vanish. The image was never “too small.” It was the wrong shape.

As for resolution: 1080 pixels wide is enough for feed posts. Platforms compress everything you upload anyway, and a 4000-pixel export gets squashed down to roughly the same file the 1080 version would have produced — sometimes with worse artefacts, because aggressive downscaling is not kind to fine text.

The four shapes, and what each is for

4:5 — the tall feed post (1080 × 1350)

This is the workhorse. It is the tallest shape Instagram allows in the feed, which means it occupies more vertical space on a phone screen than a square does — more room before the thumb moves on. It also behaves well on Facebook and LinkedIn. If you make one graphic and one graphic only, make it 4:5.

1:1 — the square (1080 × 1080)

The safest shape in existence. A square survives almost any placement without a bad crop, which makes it the right pick when the same image has to work in several places, or when you genuinely do not know where it will end up. It gives up a little screen real estate compared to 4:5, and gets that back in reliability.

9:16 — stories and reels (1080 × 1920)

Full-screen vertical, for Instagram and Facebook Stories, TikTok, Reels, and Snapchat. The critical detail here is not the size but the safe zone: the platform lays its own interface over your image — profile bubble and close button at the top, reply box and caption at the bottom. Keep anything that matters inside the middle two-thirds. Text pushed to the very top or bottom edge will collide with a UI element.

1.91:1 — the link preview (1200 × 630)

The wide banner that appears when a URL gets shared — on Facebook, LinkedIn, X, Slack, WhatsApp. This is the shape most people forget, and it is the one that quietly does the most work, because it represents your page every single time somebody pastes the link. If your site has no image set for this, the platforms improvise, and the results are rarely flattering.

The mistakes that cost you the most

In practice, the same handful of errors turn up again and again.

• Making one square and using it everywhere. It will not fail outright, which is exactly why the habit sticks. But it wastes vertical space in the feed and gets badly cropped as a link preview.
• Text too close to the edges. Give yourself a margin of roughly five per cent of the image on every side. Different apps crop by a few pixels in different places, and a headline that starts at the very edge is the first casualty.
• Type that only works at full size. Most people see your post as a thumbnail first. Look at your graphic scaled down to the size of a postage stamp: if the headline is no longer readable, it is too small, too thin, or too low-contrast.
• Screenshotting instead of exporting. A screenshot inherits your screen’s dimensions, not the platform’s, and it captures whatever compression the screen was already showing. Export properly; it takes the same ten seconds.

A note on platform specs changing

Networks adjust their crops periodically, and any article claiming a permanent table of numbers is overselling. What has been stable for years is the underlying set of shapes: tall, square, full-screen vertical, and wide. Build around those four and you are insulated from most of the churn. Before a genuinely important campaign, it is still worth a two-minute check of the platform’s current help page.

How to stop thinking about this entirely

The real fix is to stop treating sizing as a step in your process. Design the message once, then let a tool re-render it at each shape, with the layout adjusting rather than being cropped. That is the difference between exporting four sizes and cropping one image four times — the second approach loses part of your design every time.

That is exactly what PostPlex does: pick a template, type your headline, and switch between the four ratios. The type re-flows to suit each shape, and each one downloads as a PNG at the exact pixel size the platform expects — 1080 × 1350, 1080 × 1080, 1080 × 1920 or 1200 × 630. There are 24 free templates plus 16 Pro designs, and you only need a free account when it is time to download.

The short version

Four shapes cover essentially everything: 4:5 for the feed, 1:1 when it has to work anywhere, 9:16 for stories and reels, 1.91:1 for link previews. Export at 1080 pixels wide, keep your text away from the edges, and check it as a thumbnail before you post. That is the whole discipline — and it takes far less time than reading the spreadsheet.