How to Change Instagram Post Size

Ever uploaded the perfect picture to Instagram, only to watch in frustration as it crops out Uncle Jim or the beautiful mountain peak you just climbed? You're not alone. Figuring out how to change your Instagram post size to fit the platform's strict dimensions can feel like a guessing game, but it's straightforward once you understand the rules. This guide will walk you through exactly how to resize your photos and videos for the Feed, Stories, and Reels, so your posts always look just how you intended.

Why Instagram Post Size Matters More Than You Think

Instagram is a visual platform, and how your content appears on the screen has a huge impact. Posting an image with the wrong dimensions means Instagram will automatically crop it, which can mess up your composition, cut off important details, or reduce the overall quality. When you optimize the size of your images and videos, you take back control. The biggest benefit? Using the right aspect ratio - specifically the portrait orientation - allows your post to take up more vertical screen real estate, grabbing your followers' attention for a little longer as they scroll. A properly formatted post just looks more professional, polished, and on-brand.

The Official Instagram Aspect Ratios You Need to Know

Before you can resize anything, you need to know what you're aiming for. An "aspect ratio" is just a way of describing the shape of an image or video by comparing its width to its height. Instagram supports a few key ratios for different types of content.

• Square (1:1): The classic Instagram format. A 1:1 ratio means the width and height are equal. Think of a perfect square. The ideal pixel size is 1080 x 1080 pixels.
• Portrait (4:5): This is the hero format for feed posts. A 4:5 ratio is a vertical rectangle that takes up the most space in a user's feed. Aim for 1080 x 1350 pixels to achieve this.
• Landscape (1.91:1): This is for horizontal images. It's much wider than it is tall and is best for showcasing panoramic shots. The recommended size is 1080 x 566 pixels. Use this one sparingly on the main feed, as it occupies the least amount of screen space.
• Stories &, Reels (9:16): This is the format for all full-screen, vertical content. At 1080 x 1920 pixels, it's designed to fill an entire smartphone screen and is non-negotiable for Reels and an absolute must for polished Stories.

How to Change Post Size Directly in the Instagram App

You can make some basic resizing adjustments right before you post. This method is quick and works well for single images, but it offers limited control.

For a Single Photo or Video Post:

1. Open Instagram and tap the "+" icon at the bottom of the screen to create a new post.
2. Select the photo or video you want to upload from your gallery.
3. By default, Instagram will likely show your image cropped into a square (1:1). Look for a small icon in the bottom-left corner of the preview image. It looks like two corners (◆).
4. Tap this icon! It will toggle between the default square crop and the image's original aspect ratio. If your original image is a tall portrait or a wide landscape, it will snap to the closest supported size (like 4:5 or 1.91:1).
5. Once you're happy with the crop, tap "Next" to continue with your filters, caption, and tags.

This works well for a one-off photo, but you're stuck with whatever the app decides is the best fit for your original image shape.

What About Carousel Posts?

Carousel posts introduce a tricky limitation: the first photo or video you select sets the aspect ratio for all the other items in the carousel.

For example, if the first image you pick is best suited for a 1:1 square format, every other photo you add - even the vertical ones - will be forced into that same square crop. This is a common source of frustration, as you can't mix portrait, square, and landscape images in a single carousel without awkward cropping. The trick here is to decide on your aspect ratio ahead of time and crop all your photos to that size before you even start creating your carousel in the app.

The Best Method: Resizing Your Content Before You Upload

To gain complete control and avoid any surprises from Instagram's auto-cropping, the best strategy is to resize your images and videos before you upload them. This ensures every piece of content meets the exact dimensions you want. There are hundreds of tools available, but here are a few simple and popular options.

Using a Free Tool like Canva

Canva is a user-friendly graphic design tool with a great free version that makes resizing incredibly simple.

1. Go to Canva.com or open the Canva app.
2. Click “Create a design” in the top-right corner, then select “Custom size.”
3. Enter the pixel dimensions for your desired post type. For example:
   • For a high-quality portrait post, enter 1080 for width and 1350 for height.
   • For a perfect square, enter 1080 x 1080.
   • For an Instagram Story or Reel, enter 1080 x 1920.
4. Once your blank canvas appears, simply drag and drop your photo or video onto it. You can move it around and adjust the zoom until you are happy with the composition.
5. When you're finished, hit "Share" then "Download" to save the perfectly sized image or video to your device.

Using Your Phone's Built-in Photo Editor

Your smartphone is a powerful editing tool! Both iPhones and Androids have simple cropping features right in their native photo apps. This is the quickest way to fix an aspect ratio without downloading any apps.

For iPhone (Photos App):

1. Open the image in your Photos app and tap “Edit.”
2. Tap the “Crop” icon at the bottom (it looks like a square with arrows).
3. Tap the aspect ratio icon in the top-right corner (it looks like three interlocking rectangles).
4. From the list at the bottom, select the aspect ratio you need. Both "Square" (1:1) and vertical options like "4:5" should be there. For 9:16 (Stories), you can usually choose "16:9" and then hit the vertical orientation button.
5. Adjust which part of the image appears in the crop frame, then tap "Done."

For Android (Google Photos/Gallery App):

1. Open the image in your gallery and tap "Edit."
2. Look for a "Crop" tool.
3. Once in the crop tool, you should see an icon for aspect ratios (it might look like a single rectangle with a line through it).
4. Select your desired ratio, such as 1:1, 4:5, or 16:9 vertical for Stories.
5. Adjust the frame and save your masterpiece.

Troubleshooting Common Resizing Issues

Sometimes things still go wrong. Here's how to fix the most common sizing problems.

• "My photo looks pixelated or blurry after I post it." This happens when you try to resize a small, low-resolution image to make it larger. The resizing software has to guess what the new pixels should look like, resulting in a loss of sharpness. Always start with the largest, highest-quality image you have. It's better to crop a big photo down than to stretch a small one up.
• "Instagram is still cropping my photo even after I resized it!" If this happens, your crop probably isn't locked to the exact ratio Instagram supports. A ratio of 4:5.1, for example, is just off enough that Instagram will crop it to 4:5. When using editing tools, be sure to use preset aspect ratios like "4:5" instead of dragging the crop box freely.
• "My beautifully-edited text is getting cut off in my Stories!" When designing for Instagram Stories and Reels in a 9:16 format, remember the "safe zones." Instagram overlays usernames, captions, and like/comment buttons around the edges of the screen. Keep any important text, logos, or faces toward the center of your design so they aren't hidden by the user interface.

Final Thoughts

Getting your Instagram post size right boils down to mastering a few key aspect ratios and preparing your content before you hit "post." By using simple tools to resize your visuals to 4:5 for feed posts and 9:16 for full-screen content, you take back creative control and make your profile look sharp, intentional, and thoughtfully curated.

Of course, having your content perfectly sized is just one piece of the puzzle. We designed Postbase to streamline the rest of the workflow. Because our platform was built from the ground up for today's formats like Reels, Shorts, and Stories, you can schedule all your perfectly-sized content - from portrait feed photos to full-screen vertical videos - all from one clean planning calendar. You just upload it once, and we make sure it publishes on all your platforms looking exactly as it should, without any last-minute formatting headaches.