Contents
Why use this aspect ratio converterHow to change a video's aspect ratio in 3 stepsThe four shapesPick the right fill for your videoUse the aspect ratio changer on any deviceSafe, private and freeAspect ratio converter vs other waysPopular usesHow the aspect ratio converter worksAspect ratio changer features at a glanceFor developers: the ffmpeg commandFrequently asked questionsEvery platform wants a different shape: 9:16 for TikTok, Reels and Shorts, 4:5 or 1:1 for feeds, 16:9 for YouTube. Rekreate's free aspect ratio converter reshapes any video for any of them.
You choose how: fill the frame with a blurred copy of the video (the look you see on Reels), add black bars to keep everything, or crop to fill the screen.
Why use this aspect ratio converter
Convert 16:9 to 9:16 for TikTok and Reels
Turn a horizontal video into a full-screen vertical one at 1080×1920.
Add a blurred background to a video
Keep the whole picture and fill the empty space with a blurred copy of it.
Make a video square
Convert to 1:1 for feed posts.
Three ways to fit
Blurred background, black bars or crop — pick what suits the video.
Never stretched
The picture is always fitted, never distorted.
No watermark, no sign-up
Free and clean.
How to change a video's aspect ratio in 3 steps
Upload the video
Drop it into the box at the top or tap to choose it.
Choose the shape and the fill
Pick 9:16, 1:1, 4:5 or 16:9, then blurred background, black bars or crop.
Download
Press Start and save the reshaped MP4.
The four shapes
Pick the right fill for your video
Blurred background
The whole video stays visible in the middle, with a soft blurred copy filling the top and bottom. Best when a crop would cut people or text.
Black bars
The whole video stays visible with black above and below. A clean, classic look for film clips.
Crop to fill
The video fills the entire screen and the sides are cut. Best when the subject is in the center.
9:16 for TikTok, Reels and Shorts
One vertical export works on all three.
4:5 and 1:1 for feeds
Take up more of the screen than a horizontal video in a feed.
16:9 for YouTube
Turn a vertical clip into a horizontal one for YouTube or a presentation.
Use the aspect ratio changer on any device
On Windows PC and Mac
Reshape videos in any browser on Windows or Mac.
On iPhone and Android
On iPhone or Android, choose a video and save the vertical or square version straight to your phone.
In any modern browser
Chrome, Safari, Edge and Firefox all work. There is no app, plugin or extension to install — the processing happens on our servers, so an old laptop is as fast as a new one.
Safe, private and free
No account, no sign-up
Open the page and use it. There is nothing to register and no email address to hand over.
Files deleted automatically
Your upload is deleted the moment processing finishes, and the result 60 minutes later. Files are not shared, published or used for anything else.
Encrypted in transit
Uploads and downloads go over HTTPS, the same encryption your bank uses in the browser.
No watermark, ever
The file you download is clean. No logo in the corner, no intro card, no "made with" frame at the end.
Aspect ratio converter vs other ways
vs. cropping alone
A crop can cut people out of the shot. The blurred background keeps the whole picture.
vs. letting the platform do it
Uploading a horizontal video to Reels leaves it small in the middle of the screen. Converting first fills the frame.
vs. editing apps
Many apps add the blurred background only in a paid version or with a watermark.
Popular uses
Post a YouTube video on TikTok
Convert 16:9 to 9:16 with a blurred background.
Turn a landscape clip into a Reel
Fill the vertical screen without cutting anyone off.
Make a square Instagram post
Convert to 1:1 for the feed.
Put a vertical video on YouTube
Convert 9:16 to 16:9 with a blurred background.
Repurpose one video for every platform
Export 9:16, 4:5 and 16:9 versions of the same clip.
How the aspect ratio converter works
Your video is uploaded over HTTPS and processed on Rekreate's servers with FFmpeg. For a blurred background, the video is used twice: one copy is enlarged to fill the new frame and blurred, and the original is fitted on top in the center. Black bars fit the video inside the frame and fill the rest with black. Crop enlarges the video until it fills the frame and trims the overflow.
The result is a full-resolution H.264 MP4 (1080×1920 for 9:16) with the original sound. Uploads are deleted after processing, results after 60 minutes.
Aspect ratio changer features at a glance
| Shapes | 9:16 (1080×1920), 1:1 (1080×1080), 4:5 (1080×1350), 16:9 (1920×1080) |
|---|---|
| Fill | Blurred background, black bars or crop |
| Input formats | MP4, MOV, WebM, MKV, AVI, M4V |
| Output | MP4 (H.264), original sound |
| Price | Free |
| Sign-up | Not needed |
| Watermark | None |
| File size | Up to 95 MB per file |
| Video length | Up to 10 minutes |
| Files kept | Upload deleted after processing, result after 60 minutes |
For developers: the ffmpeg command
A 9:16 version with a blurred background on your own machine.
ffmpeg -i input.mp4 -filter_complex "[0:v]split=2[bg][fg];[bg]scale=1080:1920:force_original_aspect_ratio=increase,crop=1080:1920,gblur=sigma=28[b];[fg]scale=1080:1920:force_original_aspect_ratio=decrease[f];[b][f]overlay=(W-w)/2:(H-h)/2[v]" -map "[v]" -map 0:a? -c:v libx264 -crf 20 -c:a copy output.mp4gblur=sigma=28- How strong the background blur is.
Frequently asked questions
How do I change a video from 16:9 to 9:16?
Upload it above, choose 9:16 and a fill, and press Start. Blurred background is the most popular choice for Reels and TikTok.
How do I add a blurred background to a vertical video?
Choose 9:16 and "Blurred background". The video stays whole in the middle with a blurred copy behind it.
Will my video be stretched?
No. It is fitted or cropped, never stretched.
Which fill should I choose?
Blurred background when a crop would cut people or text; crop when the subject is centered; black bars for a clean cinematic look.
What size is the 9:16 video?
1080×1920, full HD vertical.
Can I convert a vertical video to horizontal?
Yes, choose 16:9. A blurred background is usually the best-looking option.
What aspect ratio does Instagram use?
9:16 for Reels and Stories, 4:5 or 1:1 for feed posts.
Can I do this on my phone?
Yes, on iPhone and Android.
Is there a watermark?
No.
What is the maximum size?
Up to 95 MB and 10 minutes.
Does the sound change?
No.
Can I choose which part stays when cropping?
The crop mode keeps the center. To keep the left or right, use the video cropper.
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