Video aspect ratio converter

How do you convert a video to another aspect ratio?

Upload the clip, pick the target ratio, choose how to fit it, and press Convert. The finished MP4 appears as a download button below the progress bar.

1. Upload a video up to 200 MB. A preview appears on the right with the source size under it, for example "Source: 1920×1080".
2. Pick a target. Each button shows the output size the converter writes:

3. Choose a fit. Crop, or fit with a blurred background. Both are explained below.
4. Set the focus point if you chose crop. Drag the blue dot on the preview, or click the preview and use the arrow keys. The white box shows the part of the frame that will be kept.
5. Press Convert. The first time, the tool downloads its video engine (about 31 MB). After that, a progress bar shows the conversion.
6. Download the file. It is named after your original with the ratio added, for example clip-9x16.mp4.

Which aspect ratio does each platform want?

Check the placement's own spec page before you convert, because ratios differ by placement, not just by platform. Two examples from official pages, checked 12 Oct 2026:

• TikTok In-Feed ads accept 9:16, 16:9 and 1:1, with 9:16 recommended and a minimum of 540×960 for vertical video, per TikTok's Auction In-Feed Ads page.
• YouTube Shorts ads recommend 9:16 at 1080×1920. Square and horizontal are supported, and horizontal video serves with blurred bars above and below, per Google Ads' Shorts asset specs.

The ad specs hub has the placement tables for TikTok, Instagram, Meta and YouTube Shorts, each with its source and checked date.

Should you crop or use a blurred background?

Crop when the subject sits in one part of the frame and the rest can go. Use the blurred background when nothing can be cut, such as a wide product shot or a frame with text near the edges.

How the crop is worked out: the converter takes the largest rectangle with the target's shape that fits inside your video, centres it on the focus point, keeps it inside the frame, and scales it to the output size.

How the blurred fit is built: one copy of the video is enlarged to fill the frame, cropped to size and blurred. A second copy is scaled down to fit inside the frame and placed in the centre on top of it.

Worked example: a 1920×1080 clip to 9:16

Upload a 1920×1080 landscape clip, choose 9:16 and Crop, and leave the focus point in the centre. The note under the preview reads "Crop: 606×1080, scaled to 1080×1920."

The kept strip is 606 pixels wide and is scaled up to 1080 wide. That is why a landscape source looks softer after a vertical crop: there are fewer real pixels to work with.

Going the other way works the same. A 1080×1920 vertical clip converted to 1:1 keeps a 1080×1080 square starting 420 pixels from the top when the focus is centred. Converted to 4:5, it keeps 1080×1350 starting 284 pixels down.

What does the converter output?

Every file is an MP4 with H.264 video and AAC audio, ready for ad platforms and editors. The exact settings:

• Video: H.264 (libx264), quality setting CRF 23, the veryfast preset, yuv420p colour.
• Audio: re-encoded to AAC at 128 kbps.
• Fast start: the file's index is moved to the front, so it can start playing before it fully downloads.
• Size: the fixed output size for the ratio you picked, from the table above.

Length is not changed. The tool does not trim, add captions or change the frame rate.

What are the limits of the converter?

• 200 MB per file. Larger files are refused before conversion, because they can run out of browser memory.
• Speed depends on your device. The work happens on your computer or phone, not on a server, so long clips take longer on slower devices.
• One focus point per clip. The crop stays in one place for the whole video. If the subject moves across the frame, use the blurred fit or reframe the clip in your editor.
• Upscaling cannot add detail. A crop from a small source is enlarged to the output size.
• The engine download. The first Convert downloads about 31 MB from a public code CDN (unpkg). Your video is not part of that request.
• Safe zones are not checked. A vertical crop can push text or the product under platform buttons. Run the result through the safe zone checker before you post it.

When one ad goes out in several ratios, convert each version from the same master file rather than from an earlier conversion, so quality is not lost twice. One script, every format covers making the versions themselves, and the ad mockup generator shows how the converted clip sits in a feed or story frame.

If you make AI ads that already perform on paid traffic, see how Anglr works for creators. All free tools are listed on the tools page.