Pad a Video to an Aspect Ratio
Pick a video, a target ratio and a bar style — solid color or blurred background. The whole frame is kept and letterboxed in your browser; nothing is uploaded.
Letterbox or pillarbox a video to any aspect ratio
Social platforms all want a different frame: 9:16 for Reels, Shorts and TikTok, 1:1 for square feed posts, 4:5 for Instagram portrait, 2:3 for Pinterest, 16:9 for YouTube. This tool fits your whole video onto the target canvas — nothing is cropped and nothing is stretched. The frame is scaled to fit, centered, and the leftover space is filled either with solid bars in the color you choose (letterbox = bars above/below, pillarbox = bars at the sides) or with a blurred, zoomed copy of the video itself — the backdrop look TV news uses for portrait phone clips. Everything runs in your browser with ffmpeg; the file never leaves your device.
Worked example
A landscape 1920×1080 clip padded to 9:16 comes out as exactly 1080×1920: the clip is scaled to fit the 1080-pixel canvas width (≈1080×606) and centered, leaving ≈657-pixel bars above and below in your chosen color — ready to post as a Reel or Short. The same clip padded to 1:1 becomes 1080×1080 with bars above and below; a portrait phone video padded to 16:9 gets bars on the left and right instead. Tick blurred background and those bars become a soft, magnified blur of the footage instead of a flat color.
Notes and limits
- The output is always exactly the target canvas: the platform-standard size for the chosen ratio (9:16 → 1080×1920, 1:1 → 1080×1080, 16:9 → 1920×1080, 4:5 → 1080×1350, 3:4 → 1080×1440, 4:3 → 1440×1080, 3:2 → 1620×1080, 2:3 → 1080×1620, 21:9 → 2520×1080), or your width × the ratio-derived height.
- A custom width must be an even number from 16 to 4096 (H.264 requires even dimensions); odd values are rejected, not silently changed.
- Bar color takes any CSS color name (
black,white,navy, …) or hex like#1A2B3C/#f0f— the same 140 names ffmpeg itself understands. The swatch next to the field picks a hex visually; typing a name works too. - Quality maps straight to x264 CRF — high = CRF 18 (bigger file), medium = CRF 23 (the default), low = CRF 28 (smaller file). No hidden "premium" tiers; the numbers are the whole story.
- Videos up to 25 MB are supported. Video re-encodes as H.264 with the
mediumpreset. Audio is stream-copied when the input keeps its container (mp4/mov/m4v/mkv); other inputs (webm, …) are converted to MP4 and the audio is re-encoded to AAC. MP4/MOV outputs are written with+faststart, so players can start streaming before the file finishes downloading. - A small clip is scaled up to the standard canvas — set a smaller width if you want to keep the original pixel size.
FAQ
Does padding crop or distort my video?
No — that's the point of padding. The whole frame is scaled to fit inside the target canvas (never beyond it), so every pixel of your original video stays visible. Bars fill the leftover space. If you'd rather fill the frame and lose the edges, use the crop tool instead.
Should I pad, crop, or stretch to change aspect ratio?
Pad (this tool) when nothing may be lost — interviews, screen recordings, anything with content near the edges. Crop when the subject sits safely in the center and you want the frame completely filled. Stretch distorts faces and almost never looks right. The blurred-background option is the middle path: the frame is filled edge-to-edge, but your whole video stays visible on top.
How does the blurred background work?
The video is used twice: one copy is zoomed until it covers the whole target canvas, center-cropped and heavily blurred to become the backdrop; your untouched full frame is then centered on top. The blur strength scales with the output size, and the bar color setting is ignored while the box is ticked.
Is my video uploaded to a server?
No — ffmpeg runs in your browser tab via WebAssembly; the file never leaves your device. You can verify it yourself: open the browser's developer tools, watch the network panel while converting, and you'll see no upload request.
Which aspect ratio should I pick for each platform?
Use 9:16 for Instagram Reels, YouTube Shorts and TikTok, 1:1 or 4:5 for feed posts, 2:3 for Pinterest, 16:9 for YouTube and most landscape players, 3:2 to match classic photo frames, and 21:9 for a cinematic letterbox look. The dropdown lists the exact pixel canvas each preset renders.
Why is the output 1080×1920 when my video was much smaller?
By default the tool renders the platform-standard canvas for the chosen ratio, which is what the apps expect (e.g. 1080×1920 for 9:16). If you want to keep your clip's own scale, set width to your video's width — the height still follows the target ratio and only bars are added.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool video-aspect-pad 'url=https://example.com/input' 'aspect=9:16' 'blur=true' 'quality=medium'New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/video-aspect-pad/?url=https://example.com/input&aspect=9%3A16&blur=true&quality=medium