How to resize ads with AI for every placement

Key takeaways

• Resizing isn't cropping. A crop cuts the frame to a new shape and loses whatever falls outside it. An AI resize re-composes the ad, moving the subject and copy and extending the background where needed.
• Three ratios cover most paid social. 1:1, 4:5 and 9:16 together cover about 80% of paid social placements. Add 16:9 and 1.91:1 for YouTube, LinkedIn and display.
• On Melius, one image becomes every ratio in one step. Magic Resize generates a re-composed version for each ratio you pick, in parallel, from the original image.
• Video ads resize differently. A vertical story often needs a different shot from a widescreen one, so the reliable route is to generate each ratio from the same brief rather than reflow one clip.
• Check every version before it ships. A layout that works at 9:16 can push the logo or the call to action off the frame at 1:1, and platform UI covers the edges of vertical ads.

Resizing ads with AI for every channel

To resize an ad with AI, you give a finished image or video to a tool that re-composes it for each aspect ratio you need, rather than cropping it, so the product, the copy and the logo stay inside the new frame. On Melius, Magic Resize does this for images in one click: pick the ratios, run it, and a properly composed version appears for each one. For video, you set the ratio on the video node and generate each format from the same brief.

Every paid placement wants its own shape. Instagram Stories and Reels are vertical, Facebook and Instagram feeds favor 4:5, YouTube in-stream is widescreen, and LinkedIn and Google display lean on 1.91:1. One ad becomes five or six files, and doing that by hand is the kind of work that eats an afternoon without adding anything creative to the ad.

Why cropping breaks an ad

Cropping keeps the original composition and cuts it down to the new shape. When going from a square to a vertical story, you lose the sides. When going from vertical to widescreen, you lose the top and bottom. Subjects get clipped at the edge, headlines lose their first or last word, and the product slides out of the frame. Meta's Advantage+ creative can also adjust an ad's aspect ratio automatically when you don't supply a format for each placement.

An AI resize treats the new ratio as a new layout. It moves the subject, repositions the copy and generates new background where the frame grows, so each version looks designed for its placement. That's the difference the term "generative expand" points at, and it's why an AI resize can go from square to 16:9 without leaving bars or an awkward zoom.

Ad sizes by platform

The ratios and sizes each platform recommends in its own ad specs, as of October 2026. Where a platform lists several, the first is its recommended format.

LinkedIn serves its 4:5 vertical images on mobile only. YouTube Shorts accepts horizontal video, but shows it with blurred bars above and below.

How to resize an image ad on Melius

These are the steps from our resize for channels recipe. Start from a finished ad: resizing a draft locks in compositional choices you might still want to change.

1. Open Magic Resize. Right-click the image node, or select it and use the toolbar on the right.
2. Pick the ratios you ship to. A grid offers 1:1, 4:5, 9:16, 16:9, 4:3, 3:4, 21:9 and more. Click each one you need. If you're unsure, start with 1:1, 4:5 and 9:16.
3. Run it. The versions generate in parallel into a magic resize node that holds one image per ratio, connected to the original.
4. Set the output to 2K or higher. The canvas preview is downscaled, so a version that looks sharp there may be 1K underneath. Raise the resolution before you download.
5. Review in full-screen. Double-click a result to open it. Every ratio from the run is listed down the left, the arrow keys move between them, and each one's details follow the version on screen. Download one ratio from the viewer, or the whole set from the node's toolbar.

For a brand look carried across a set of statics, see how to make a static ad from a style reference.

Resizing a whole batch of ads at once

When you have a set of finished ads rather than one, brief Mel, the Melius agent, instead of resizing each by hand. The brief fits in one line: take every image node in the "winners" group and run Magic Resize on each, generating 1:1, 4:5 and 9:16 versions of all of them. The agent queues every resize job in parallel.

Pick only the ratios you actually run. Eight ratios on one ad is a little wasted time, while eight ratios on each ad in a 50-variant test is a lot of it. Teams on the API or the mel command-line tool can call the same resize from their own scripts.

How to resize a video ad with AI

A video ad is harder to resize than an image, because the composition moves. An editor's auto reframe, such as the one in Premiere Pro or CapCut, detects the main action and reframes each shot around it, which works when the action stays near the center. It still cuts the frame down, so a product held at the edge of a widescreen frame can fall out of a vertical one.

A 16:9 frame and a 9:16 story sometimes need entirely different shot composition, not the same shot reflowed, so we recommend generating each from the same brief. In practice that means one brief, one set of references and several video nodes, each set to the ratio its placement needs. Select the video nodes together and change Aspect ratio once in Generation settings to set them all; the change applies to the next generation, so existing clips keep their dimensions. For the wider test workflow, see our guide to AI video ad creative variants.

If you already have a vertical clip you like, its starting frame can carry the look across. Resize that frame as an image, then use each version as the starting frame of a new video node at the matching ratio, with the same motion prompt.

Where resized ads go wrong

• Copy under the platform's UI. Meta suggests keeping roughly 14% at the top, 35% at the bottom and 6% on each side of a Stories or Reels ad free of text, so the profile icon and call-to-action button don't cover it. TikTok publishes its safe zones as downloadable templates.
• Too much invented background. Going from 9:16 to 21:9 asks the model to invent most of the frame. That's usually fine for environmental shots and can break tight product or portrait compositions, so regenerate those from the brief instead.
• A logo or CTA pushed out of frame. A layout that worked vertically can lose its call to action at 1:1. Spot-check every version against your brand anchor before it ships.
• Shipping the preview resolution. What you see on the canvas isn't the final file. Set 2K or higher and confirm the dimensions in the full-screen view before you download.

How other tools handle ad resizing

The common options split by format, as of October 2026. For images, Canva's resize, which its help center calls Magic Resize and its video page calls Magic Switch, reflows a design into a new format, and Canva's Magic Expand and Adobe's Generative Expand in Firefly and Photoshop extend a photo beyond its frame. For video, Adobe Express's video resize scales a clip to a social preset, while Premiere Pro and CapCut offer Auto Reframe, which detects the main action and reframes it for each ratio.

Most of these are one step inside a larger editor. The difference on Melius is that the resize sits next to the generation that made the ad: the brief, references and brand anchor are on the same canvas, so a version that needs regenerating instead of resizing is one node away.

Why resize ads on Melius

Melius is the AI-native operating system for creatives, built on a node-based canvas. Each ad, reference and set of resized versions is a node connected back to its source, so a fix to the original carries forward and every ratio stays traceable to the ad it came from.

You brief Mel to resize a whole test set then review every version before it ships. Each node is editable, so you can make changes to individual steps rather than recreate the entire ad. Generation, editing and resizing run on one subscription across a library of leading models. Resizing sits alongside variants, localization and animated statics on Melius for marketers.

You own the content you create on Melius and can use, publish, and distribute it commercially, subject to the underlying model providers' terms. Melius doesn't claim ownership of your work and doesn't use it to train AI models.

Frequently asked questions