Convert 16:9 to 9:16
without cropping.
There are three ways to fit widescreen into vertical, and only one of them keeps your whole frame. Here's the comparison and the command.
Three approaches, compared
| Method | Keeps full frame? | Fills screen? | Best for |
|---|---|---|---|
| Crop to fill | No — loses ~70% width | Yes | Single centred subject, talking head |
| Letterbox (black bars) | Yes | No — wastes ~50% | Archival, where format fidelity matters |
| Blurred fill | Yes | Yes | Almost everything else |
Blurred fill is the only option that keeps the entire frame and uses the whole screen, which is why it's become the default for reposted widescreen content.
What cropping actually costs you
A 1920×1080 frame cropped to 9:16 keeps a centre strip roughly 608 pixels wide. That's about 32% of the original width — you're discarding two thirds of everything that was in shot.
For a single person centred on camera, that's survivable. For a stream layout, a gameplay scene, or anything with two subjects, it usually removes the thing that made the video worth posting.
Blurred fill, exactly
ffmpeg -y -i input.mp4 -filter_complex "\
[0:v]scale=1080:1920:force_original_aspect_ratio=increase,\
crop=1080:1920,boxblur=40:4,setsar=1[bg];\
[0:v]scale=1080:-2[fg];\
[bg][fg]overlay=(W-w)/2:(H-h)/2:format=auto,format=yuv420p[v]" \
-map "[v]" -map 0:a? -c:v libx264 -preset veryfast -crf 20 \
-c:a copy -movflags +faststart output.mp4If you genuinely want to crop instead
ffmpeg -y -i input.mp4 -vf "scale=-2:1920,crop=1080:1920" \
-c:v libx264 -crf 20 -pix_fmt yuv420p -c:a copy output.mp4Only worth it when your subject is reliably centred for the entire duration.
Why the height is -2 and not a number
H.264 requires even pixel dimensions. Writing scale=1080:-2 tells ffmpeg to work out the height from the width, preserve the aspect ratio, and round to the nearest even number.
Hardcoding a height instead — say scale=1080:608 — assumes the source is exactly 16:9. Plenty of real footage isn't (ultrawide captures, cropped recordings, odd stream resolutions), and every one of those comes out subtly stretched. It's a bug that's easy to miss until someone points at your video and says it looks off.
Common questions
What is 9:16 in pixels?
1080 × 1920 is the standard. That's the native resolution for TikTok, Instagram Reels, and YouTube Shorts.
Is blurred fill better than cropping?
For most content, yes — it keeps the entire frame while still filling the screen. Cropping only works well when your subject stays centred throughout.
Does letterboxing hurt performance?
Black bars waste around half the screen and read as low-effort on short-form platforms, which tends to reduce watch time.
Why must dimensions be even?
H.264 encodes in blocks and requires even width and height. Using -2 in the scale filter handles this automatically.