What aspect ratio should I use for Instagram?

4:5 portrait, which is 1080 x 1350 pixels. It is the tallest the feed accepts without cropping, so it takes the most vertical space as someone scrolls. Square at 1:1 also works and is easier to reuse elsewhere.

How do I convert 16:9 to 9:16 without ruining it?

You cannot do it without losing about 44% of the width, or adding padding. For video, most editors let you reframe so the crop follows the subject. For stills, re-crop deliberately rather than letting the platform pick the centre.

What does the decimal ratio mean?

Width divided by height. 1.7778 is 16:9, 0.8 is 4:5, 0.5625 is 9:16. It is useful when a tool asks for a ratio as a single number rather than two.

Does resizing change the aspect ratio?

Not if you scale both dimensions by the same factor, which is what this calculator does. Changing one dimension alone stretches the image, which is the most common way an asset ends up looking subtly wrong.

Aspect ratio calculator

Work out any aspect ratio, resize without distorting, and see how much each platform crops off.

Free. No sign-up. Runs in your browser. Checked 2026-09-09.

Your image

Width (px)

Height (px)

Aspect ratio: 16:9
As a decimal: 1.7778
Closest standard: Landscape (YouTube, X)

Resize while keeping the ratio

New width (px)

= 1080 × 608

What each platform does to this image

Assuming the frame is filled and the overflow cropped, which is what every platform does by default.

Target	Size	Ratio	Cropped
Instagram Feed post (portrait)	1080×1350	4:5	55% off the sides
Instagram Feed post (square)	1080×1080	1:1	44% off the sides
Instagram Story / Reel	1080×1920	9:16	68% off the sides
LinkedIn Feed image	1200×1200	1:1	44% off the sides
YouTube Video thumbnail	1280×720	16:9	Fits
Pinterest Standard pin	1000×1500	2:3	63% off the sides

How this works, what it excludes, and the FAQsShow

Why the crop table matters more than the ratio

Knowing your image is 16:9 is not useful on its own. What you need to know is what happens when you put it somewhere that expects 9:16, and the answer is that nearly half of it disappears.

Every platform fills its frame and crops the overflow. The table shows which axis is cut and by how much, so you can re-crop deliberately or design at the right ratio in the first place.

The ratios worth knowing

4:5 is the Instagram feed maximum — the tallest a feed post can be without cropping, and therefore the most screen space. 9:16 covers stories, reels, TikTok and Shorts. 1:1 is the safest cross-platform ratio because everything crops from square without losing much.

Designing at 4:5 and 9:16 covers most of a content calendar. A 1:1 export from a 4:5 master loses the top and bottom evenly, which is usually survivable if the subject is centred.

Put this calculator on your own site

Free to embed on any site, including commercial ones. Paste the snippet into a blog post, a resources page or a client-facing guide and the calculator runs inside your page.

The only thing we ask is the credit line underneath, which links back here. That link is how people find the tool and how we justify keeping it free and ungated, so please leave it in.

Currency for your readers

Leave this on automatic and each reader sees their own currency, detected from their browser and changeable by them. Pin one if your audience is in a single market.

Copy this into your page

<iframe
  src="https://poststack.ai/embed/aspect-ratio-calculator"
  title="Aspect ratio calculator"
  width="100%"
  height="1000"
  style="border:1px solid #e2e8f0;border-radius:12px;max-width:100%"
  loading="lazy"
></iframe>
<p style="font-size:14px">
  <a href="https://poststack.ai/tools/aspect-ratio-calculator">Aspect ratio calculator</a> by
  <a href="https://poststack.ai">Poststack</a>
</p>

Optional: remove the inner scrollbar

The embed works without this. Add it once anywhere on the page and the iframe resizes itself to fit its content instead of scrolling internally. It listens only for a height number from poststack.ai and does nothing else.

<script>
window.addEventListener('message', function (e) {
  if (e.origin !== 'https://poststack.ai') return
  if (!e.data || e.data.type !== 'poststack:embed:height') return
  var frames = document.querySelectorAll('iframe[src*="https://poststack.ai/embed/"]')
  for (var i = 0; i < frames.length; i++) {
    if (frames[i].contentWindow === e.source) {
      frames[i].style.height = e.data.height + 'px'
    }
  }
})
</script>

Default height: 1000px, adjustable in the snippet
Tracking: None. No cookies, no analytics, nothing posted back to us
Your readers’ data: Stays in their browser. We never receive what they type

Frequently asked questions

What aspect ratio should I use for Instagram?: 4:5 portrait, which is 1080 x 1350 pixels. It is the tallest the feed accepts without cropping, so it takes the most vertical space as someone scrolls. Square at 1:1 also works and is easier to reuse elsewhere.
How do I convert 16:9 to 9:16 without ruining it?: You cannot do it without losing about 44% of the width, or adding padding. For video, most editors let you reframe so the crop follows the subject. For stills, re-crop deliberately rather than letting the platform pick the centre.
What does the decimal ratio mean?: Width divided by height. 1.7778 is 16:9, 0.8 is 4:5, 0.5625 is 9:16. It is useful when a tool asks for a ratio as a single number rather than two.
Does resizing change the aspect ratio?: Not if you scale both dimensions by the same factor, which is what this calculator does. Changing one dimension alone stretches the image, which is the most common way an asset ends up looking subtly wrong.