Free Video Resizer & Aspect Ratio Converter
Resize videos to 9:16 vertical, 1:1 square, or any custom aspect ratio. Smart crop, letterbox, or blur-fill options. Browser-based, no upload.
Why Do This in Your Browser?
Vertical video — 9:16, the dimensions of a held phone — is now the dominant format on TikTok, Reels, Shorts, and Stories. Almost everyone shoots in 16:9 landscape. The gap between the two is filled, most of the time, by a hasty resize tool that either crops important content out or stretches the picture into something deformed.
This tool offers three intelligent resize modes: smart crop (auto-detects and follows the most active area of the frame), letterbox (preserves the entire image with black bars), and blur fill (preserves the entire image and fills the empty space with a blurred copy of the video — the technique TikTok and Reels use themselves). Pick the mode that matches your content; export.
How It Works
Smart crop runs a lightweight motion analyzer on the source video, computes the centroid of activity per frame, and pans the crop window to follow it. The result is an automatic 'virtual camera operator' that keeps important content centered as it moves across the 16:9 frame. Best for talking-head, sports, and dialog-driven content; less suited to wide landscape shots.
Letterbox is the safe option: scale the source to fit the target's width (or height, whichever leaves no overflow), and fill the rest with black. Blur fill is the cinematic option: same scale, but fill with a heavily-blurred upscaled copy of the source. Visually pleasing, and increasingly the default on social platforms.
Tip: Resize is often paired with a trim — pick the right portion, then reframe to vertical. Add captions to the resized vertical video with the Video Watermark tool before posting.
Common Use Cases
How We Compare
Honest read on free, paid, and self-hosted options for this kind of job: