The right size in numbers, and what it actually means
The number you're looking for is simple. Export at 9:16 and 1080 x 1920 pixels, which is the standard for vertical video according to the official Shorts help page. That size fills a phone screen from top to bottom, with no black bars and no empty space around the picture.
The ratio matters more than the resolution. A vertical video at a lower resolution will still fill the screen, but it may look softer. A higher resolution won't buy you much, because the app compresses every video on upload anyway. So the rule to remember is this: shoot vertical, and export at the ratio and resolution above whenever you can.
If you're shooting on your phone, hold it vertically from the start. If you're editing, pick a vertical project setting before you drop in a single clip. Changing the frame at the end means rearranging everything.
Where does Instagram crop your video? The safe zone
This is where most creators slip up. Your video fills the screen, but not every part of it stays clearly visible, because the app lays a whole set of interface elements on top.
At the bottom you get your username, then your caption, then the name of the audio. Down the right side sit the like, comment and share buttons. At the top you have the Reels header and the camera icon. Any text you put under those elements will disappear or get hard to read.
The practical rule is easy. Keep on-screen text, faces and products in the center. Leave plenty of room at the bottom, since the caption takes up more space than you'd expect. And stay a little away from the right edge because of the buttons.
Before you post, open the preview inside the app. Watch the first few seconds and make sure every line is readable. That quick check saves you from deleting the Reel and posting it again.
Does the wrong size hurt your reach?
You may have heard there's a secret size that makes the algorithm love your video. Don't buy it. Short-form platforms rank videos based on what viewers do: did they finish it, did they rewatch it, did they share it? Size isn't a magic key.
Size does have an indirect effect, though. A horizontal video with black bars above and below looks like something reposted from somewhere else. Viewers notice that in a split second and swipe to the next video. And when people swipe away fast, the video travels less.
So here's the full picture. The right size won't guarantee you views. The wrong size hands viewers one more reason to leave. What makes the difference after that is your opening, your idea, and posting consistently.
Got a horizontal or square video? Here are your options
Plenty of us have old clips shot horizontally. You don't have to throw them out. You have three options, and each one costs you something.
The first is a center crop. You take the middle of the frame and scale it up to fill the screen. This works well when the person or subject is in the middle of the shot. If the action happens at the edges, you lose it.
The second is placing the video over a blurred background. The whole picture stays intact and the screen is full. But the video itself appears small, and someone watching on a phone has to squint to catch the details.
The third is re-editing shot by shot. For each scene you choose the part that deserves to be on screen. This gives the best result, but it takes time.
My honest advice: use old horizontal clips as extra material, and don't build your channel on them. If you're going to post Reels regularly, plan every new video as vertical from the start.
The cover and your profile grid
The cover is the image that represents your video on your profile. You can pick a frame from the video or upload a custom image. The catch is that the profile grid shows a shorter version of the cover, so part of the top and bottom gets cut off.
The fix is the same rule as the video. Put the cover title in the middle and keep it short and clear. Then open your profile after posting and see how it looks next to your other videos.
There's one thing a lot of people miss. In the main Reels feed, the video starts playing automatically, so viewers see your first frame, not your cover. The cover does its job on your profile, when someone visits to decide whether to follow you. In the feed, your first frame is your real cover. So make it clear and readable from the very first moment.
If you don't want to think about sizes every time
After your first ten or so videos, setting the size and checking the safe zone turns into repetitive work. And that repetitive work is exactly what stops a lot of creators from posting consistently.
This is where MaqtAi helps if you run a faceless channel. You type a topic and choose your video format in the Length & aspect ratio step. MaqtAi then writes the script and adds an AI voiceover, animated scenes and on-screen captions. The result is a vertical video ready to post. Captions sit at the bottom by default. If you want to move them up and away from the caption area, switch the wizard from Simple to Advanced, then change the position in the Captions step. The "Generate thumbnail" button designs a vertical cover and a wide cover for each video.
Keep your expectations realistic. The tool won't pick the idea your audience loves, and it doesn't guarantee any number of views. Posting directly to Instagram Reels requires a Business or Creator account linked to a Facebook Page, plus a paid plan. Videos from a free account carry a watermark. You can still download the video and post it yourself. Full details are on the features page.
Think about the cost of waiting. Every week you spend fiddling with settings is a week with no videos. A channel learns nothing from a video that never went up, and it collects no data about your audience. Meanwhile, a competitor in your niche has been posting every day.
The small step today is one video. Most new accounts get free credits when they confirm their email, with no card required, though some accounts aren't eligible. Check the details on the pricing page, then make your first Reel and see for yourself how it looks on your phone screen.
Doing this by hand is the part most people quit at. MaqtAi writes the script, narrates it, generates the visuals and captions, and assembles the faceless short for you. Verify your email and you get 450 free credits: about 3 videos on the still-frame tier, or one with AI motion. Free renders carry a watermark.
Try it on your niche freeFrequently asked questions
Can I post a Reel with a horizontal video? Yes, Instagram accepts horizontal video. But it shows up small with empty space above and below, and viewers swipe past it more easily. You're better off cropping it or re-editing it as vertical.
Why does my Reel cover look cropped on my profile? Because the profile grid shows a shorter version of the vertical cover. Put the title and the key image in the middle of the cover and they'll show up in full.
Does a higher resolution give a video more reach? There's no evidence for that. Good resolution keeps the video sharp, but reach comes from viewer behavior, like finishing the video and sharing it.
Can I post the same video to TikTok and YouTube Shorts? Yes, the same vertical format works on all three platforms. Just watch the length: the official YouTube Shorts page says a Short can be up to 3 minutes long.