How to Change the Dimensions of an Instagram Post

Ever posted what you thought was the perfect photo to Instagram, only to see it bizarrely cropped, cutting off key details or messing up your composition? You're not alone. Mastering Instagram's dimensions is the secret to a professional-looking feed that stops the scroll. This guide walks you through exactly how to change the dimensions of an Instagram post, covering everything from the ideal sizes for different content to the tools you need to get it right every time.

Why Instagram Post Dimensions Matter More Than You Think

Taking a moment to resize your content isn't just a technical step, it’s a strategic one. Getting your dimensions right directly impacts how people experience your brand. Here's why it's so important:

• You Avoid the Awkward Crop: Instagram's number one goal is to create a seamless user experience. If your image or video doesn't fit its preferred dimensions, the app will automatically crop it for you, often with less-than-ideal results. This can lead to cut-off heads, unreadable text, or a completely ruined composition.
• You Maximize Screen Real Estate: The more space your post takes up on someone's screen, the longer you hold their attention. A vertical post (we'll get to the specifics) fills more of the screen on a mobile device than a traditional square or landscape post, making it more impactful and harder to scroll past.
• It Signals Professionalism: A visually consistent and well-composed feed is a hallmark of a professional brand. When every image is perfectly sized and nothing looks accidental, it tells your audience that you’re detail-oriented and care about the quality of your content.
• Better Composition and Engagement: When you control the crop, you control the story. Proper sizing ensures your subject is perfectly framed, and your visual narrative is clear, which can lead to higher engagement.

The Golden Rules: Ideal Instagram Post Dimensions

Instagram supports a few different shapes and sizes depending on the type of content you're posting. Let’s break down the essential numbers you need to know.

For the Main Feed (Photos and Videos)

When you post a single photo or video to your grid, you have three main choices for aspect ratios - the proportional relationship between an image's width and height.

1. Square Post (1:1 Ratio)

• Ideal Size: 1080 x 1080 pixels
• What to Know: This is the classic, original Instagram format. It's safe, reliable, and easy to compose for. Because it's perfectly symmetrical, it’s a great choice for centered subjects, text graphics, and maintaining a uniform grid aesthetic.

2. Portrait (Vertical) Post (4:5 Ratio)

• Ideal Size: 1080 x 1350 pixels
• What to Know: This is the most effective dimension for feed posts. A 4:5 vertical post takes up the most vertical space on a user's mobile screen without being cropped in the main grid view. More screen time means more attention from your audience. For marketers and brands, this is almost always the best choice for driving engagement.

3. Landscape (Horizontal) Post (1.91:1 Ratio)

• Ideal Size: 1080 x 566 pixels
• What to Know: Landscape is best for wide B-roll videos or panoramic photos. However, it takes up the least amount of screen space in the feed, making it the easiest format for users to scroll past. Use it only when the visual content absolutely demands a horizontal layout.

For Other Instagram Formats

Of course, Instagram is more than just the feed. Here are the dimensions for its other popular formats.

• Instagram Stories & Reels (9:16 Ratio): The ideal size is 1080 x 1920 pixels. This full-screen vertical format is designed for immersive, mobile-first viewing. Because these are almost always viewed on a phone, creating content in this specific size is non-negotiable for a professional look.
• Instagram Carousel Posts: Carousels can use any of the three main feed dimensions (square, portrait, or landscape). However, there's a catch: all a carousel's photos and video will be cropped to match the aspect ratio of the very first slide you select. So, if your first image is a 1:1 square, every other slide will be forced into a square format, too. It’s best to pre-size all your carousel content to the same dimension before uploading.
• Instagram Profile Picture: Your profile picture thumbnail appears as a circle on your profile, but you should upload a square image of at least 320 x 320 pixels to ensure it’s sharp.

How to Change the Dimensions of an Instagram Post: Your Step-by-Step Guide

You have a couple of options for resizing your content: before you upload it (the best way) or as you're posting it directly in the app.

Method 1: Resizing Your Post Before You Upload (Highly Recommended)

Using a simple design tool is the most reliable way to get perfect dimensions every time. It gives you full control over the final look. Tools like Canva, Adobe Express, or Fotor make this incredibly easy.

Here’s how you’d do it using Canva (the process is similar in other web-based editors):

1. Create a New Design: From the Canva homepage, click "Create a design" in the top-right corner, then select "Custom size."
2. Enter Your Dimensions: A box will pop up asking for width and height. Enter the exact pixel dimensions you need. For a knockout portrait post, you'd type 1080 for width and 1350 for height.
3. Upload and Adjust Your Image: Once your blank canvas is created, drag your photo or video file from your computer onto the canvas. Use the corner handles to resize the image to fit the frame perfectly. You can drag the image around within the frame to get the composition just right.
4. Download Your File: When you're happy with the result, click the "Share" button, then "Download." Choose a high-quality format like PNG for images or MP4 for videos, and save the final, perfectly-sized file to your device.

Resizing before you post might seem like an extra step, but it eliminates any guesswork and guarantees Instagram won't butcher your carefully crafted shot.

Method 2: Adjusting Dimensions Inside the Instagram App

Instagram gives you a limited ability to adjust the crop as you're creating a post. This method is faster but offers less precision.

1. Tap the + icon to start a new post and select your photo or video.
2. By default, Instagram may show your image cropped to a square (1:1).
3. Look for the expand icon (two arrows pointing outwards, usually in the bottom-left of the image preview). Tap this icon.
4. Instagram will automatically adjust the post to fit its original aspect ratio - as long as it fits within the acceptable limits (between 1.91:1 and 4:5). If your image is taller than 4:5, Instagram will still crop it.
5. You can use your fingers to pinch and drag the image to fine-tune the composition within the given frame.

This in-app tool is useful for quick adjustments, but for consistently professional results, Method 1 is always the winner.

Can You Change Post Dimensions After Posting?

This is one of the most common questions out there, and the answer is simple: No, you cannot edit the dimensions of an Instagram post once it has been published. You also cannot change the photo, video, or slides within a carousel you've already posted.

If you've posted something with a terrible crop and you just can't live with it, you have two options:

1. Hide it from your Profile: You can "Archive" the post, which removes it from your public grid but doesn't permanently delete it. This is a good option if you want to save the comments and likes data. You can find the archive option by tapping the three dots on your post.
2. Delete and Repost: The more common solution is to delete the post entirely, go back and resize your image or video correctly using one of the methods above, and then upload it again. You will lose any engagement you've already received, but your feed's aesthetic will thank you for it.

Don’t feel bad if this happens! Every social media manager has made this mistake. The best approach is to learn from it and make pre-sizing part of your standard content workflow.

Final Thoughts

Thinking about dimensions before you hit "Publish" transforms your content from amateur to professional. By using the optimal sizes, especially the 4:5 portrait mode, you make your posts more visually compelling, hold attention longer, and build a more polished brand presence on Instagram.

At Postbase, we built our content planner with visuals at the forefront. Our visual calendar gives you a clear preview of your entire content strategy, so you can see exactly how your perfectly-sized posts will look next to each other on your grid. This helps you curate a cohesive feed without any surprises, ensuring everything you schedule - from single images to full carousels - looks exactly as you planned.