OctosparkOctoSpark
Free tool — runs in your browser

Instagram aspect ratio calculator

Work out the right Instagram shape for a feed post, carousel, story or Reel, and solve the height for any width at 4:5, 1:1, 1.91:1 or 9:16, in the browser.

Width and height

With the ratio unlocked, each side is yours to set and the shape below follows.

Aspect ratio

4:5

A 4:5 frame.

How this is worked out

  • Reduced by their greatest common divisor: 4:5
  • Width divided by height: 0.8000
  • Both terms are small enough to print as a ratio.

Lock to a named shape

Instagram shapes

Square feed post (1:1)

The old default, and still the right answer when a carousel mixes landscape and portrait sources.

2 image resizer presets match this shape.

Portrait feed post (4:5)

The tallest a feed post may be, so it occupies more of a scrolling screen than anything else you can post.

1 image resizer preset match this shape.

Landscape feed post (1.91:1)

The widest a feed post may be, and the shape that gives up the most height in a vertical feed.

1 image resizer preset match this shape.

Story and Reel (9:16)

Full screen, with your avatar row above and the reply bar below sitting on top of the frame.

1 image resizer preset match this shape.

Every aspect ratio Instagram accepts

Instagram publishes four shapes and quietly refuses everything else, reframing anything outside that set on the way in. Knowing which four saves you finding out after a post is live.

  • Square feed post, 1:1. The old default, and still the right answer when a carousel mixes landscape and portrait sources. In our image resizer: Square post at 1080x1080px, Profile photo at 320x320px.
  • Portrait feed post, 4:5. The tallest a feed post may be, so it occupies more of a scrolling screen than anything else you can post. In our image resizer: Portrait post at 1080x1350px.
  • Landscape feed post, 1.91:1. The widest a feed post may be, and the shape that gives up the most height in a vertical feed. In our image resizer: Landscape post at 1080x566px.
  • Story and Reel, 9:16. Full screen, with your avatar row above and the reply bar below sitting on top of the frame. In our image resizer: Story / Reel at 1080x1920px.

Choosing between 4:5, 1:1 and 1.91:1

The choice is about how much of a scrolling screen you occupy and how much of your picture you are prepared to lose to get there. It is the same photograph in all three cases and three different posts.

  • 4:5 buys the most height of any feed post, which is the single cheapest thing you can change about how much attention a post gets.
  • 1:1 is the safe answer for a carousel, because Instagram applies the first slide’s shape to every slide behind it.
  • 1.91:1 gives away the most vertical space, so keep it for pictures that genuinely need their width, such as a wide landscape or a group lined up.
  • A 9:16 story or Reel is a different composition rather than a different export. The interface sits over the top and bottom of that frame, not beside it.
  • Whatever you pick, the shape is the decision and the pixel count follows it. Instagram works everything back to a 1080 pixel canvas regardless of what you send.

What Instagram does with a shape it does not support

Nothing is rejected outright, which is the problem: an unsupported shape is accepted, silently reframed and published without asking you which part mattered.

  • Anything taller than 4:5 is cropped back to 4:5, so a full-length 9:16 photo posted to the feed loses its top and bottom.
  • Anything wider than 1.91:1 is cropped back to 1.91:1, which is how a panorama becomes an unreadable strip of its own middle.
  • The crop is taken from the centre, so a subject placed off to one side goes first and the empty half of the picture stays.
  • A screenshot of text is the usual casualty. Cropping takes the lines at the edges, and the remaining ones are then rendered at a third of a phone screen.
  • Preview at the shape you are posting rather than at the shape of your original. The version you are looking at while you edit is not the one anybody else sees.

Working an Instagram size out from a ratio

Instagram publishes pixel sizes, but the shape is what it enforces, so it is usually faster to start from the shape and solve for the pixels you happen to have.

  1. Put your source width in and lock the shape you are posting to. The height you need appears immediately.
  2. Compare that height against the height you actually have. If your file is shorter, you are going to be padding rather than cropping.
  3. Keep 1080 in mind as the working width. Anything wider is scaled down before a single person sees it, so solving above that width buys nothing.
  4. For a carousel, solve once and use the same pair for every slide. A mixed set is cropped to match the first image in it.
  5. Take the resulting pixel pair to the image resizer when you are ready to export, rather than resizing by eye in a photo app.
The rest of the job

You just fixed one post. Now do the month.

The instagram aspect ratio calculator solves one piece of one post. OctoSpark plans, writes and schedules the whole calendar across every network you use, publishes it for you, and reports what actually performed.

  • One calendar for every network
  • Schedule once, publish everywhere
  • Drafts written in your own voice
  • See what actually performed
Open the full sign-up page

No card needed. These tools stay free either way.

Related free tools

Frequently asked questions

How this tool works, what it cannot do, and what happens to what you put into it.

  • What aspect ratio is best for Instagram?

    For a feed post, 4:5. It is the tallest shape Instagram allows there, so it takes the most room on a scrolling screen. Use 1:1 for carousels, where every slide has to share the first slide’s shape, and 9:16 for stories and Reels.

  • Can I post a 16:9 photo to the Instagram feed?

    Not as 16:9. The widest a feed post can be is 1.91:1, so a 16:9 picture is accepted and then cropped slightly wider than it was, taken from the centre. If the edges of the frame matter, crop it yourself first.

  • What is the difference between 4:5 and 9:16 on Instagram?

    4:5 is a feed post and 9:16 is a full-screen story or Reel. They are different surfaces rather than two sizes of the same one, and a 9:16 image posted to the feed has its top and bottom cropped away to fit 4:5.

  • Does the pixel size matter if the ratio is right?

    Less than people expect. Instagram works everything back to a 1080 pixel canvas, so as long as your source is at least that wide the shape is doing the work. Below 1080 wide, the platform is scaling up and that is visible.

  • Is my data private?

    Yes. This tool does its work in your browser, so whatever you type, paste or upload stays on your device. Nothing is sent to our servers, which is also why it keeps working if you go offline after the page has loaded.

  • Is this really free?

    Yes. Every tool here is free with no account, no credit card and no usage cap. They exist so that the people who need our scheduling product find us, which only works if the tools are genuinely useful on their own.

  • Do I need an account?

    No. Open the page and use it. An account is only for OctoSpark itself, where you plan, schedule and publish a whole calendar rather than fixing one post at a time.

  • Can I use the output commercially?

    Yes. Anything you produce here is yours, including for client and commercial work. We claim no rights over it and we do not watermark it.