Resize videos to 1080p, 720p, 480p, 360p, or custom dimensions, processed entirely in your browser, files never uploaded.
Your video is resized locally with FFmpeg running in your browser. Nothing is uploaded; the file never leaves your device. First use downloads the ~31 MB engine once. Files up to 200 MB.
Height presets lock the source aspect ratio: the width is calculated automatically and rounded to an even number. Custom applies the exact dimensions you enter.
Both values must be even numbers between 16 and 7680; H.264 cannot encode odd dimensions. A ratio different from your source will stretch the picture.
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Resolution mismatches are one of the most common video headaches: 4K phone footage too heavy to email, a screen recording headed for a platform that caps playback at 1080p, or a clip that needs to drop to 480p so it plays smoothly on an older laptop. Resizing changes the pixel dimensions of every frame (1920×1080, 1280×720, and so on), which usually shrinks the file as well, since there are simply fewer pixels to encode.
The height presets (1080p, 720p, 480p, 360p) lock the source aspect ratio: FFmpeg's scale filter derives the matching width automatically and rounds it to an even value, so nothing is stretched or squashed. Custom mode applies exactly the width and height you enter ( useful when a target demands precise dimensions), but if that ratio differs from your source the picture will be distorted. When you need a different aspect ratio without distortion, cutting the frame down with the Video Cropper is the right approach.
Resizing re-encodes the video track (H.264, constant quality CRF 23) while copying the audio untouched, so quality loss is minimal for a single pass. If your real goal is a smaller file at the same dimensions, the Video Compressor does that job directly; to shorten the clip instead of scaling it, use the Video Trimmer.
Usually, yes: downscaling means fewer pixels per frame, so the re-encoded file is typically smaller than the source. But this is not primarily a compression tool: for the smallest possible file at the same dimensions, use the Video Compressor instead.
H.264 encodes video in macroblocks and requires every dimension to be divisible by two; odd widths or heights make encoding fail outright. The height presets never hit this problem because the scale filter rounds the computed width to an even value automatically.
The height presets never do; the width is derived from your source, so a 16:9 video stays 16:9 at any preset. Custom dimensions can: entering 1280×720 for a 4:3 source stretches the picture. If you need a different aspect ratio without distortion, crop the video instead.
You can, but it will not add detail; the output just interpolates the existing pixels, so it looks soft and may even grow in file size. Upscaling is only worth it when a platform strictly requires a minimum resolution.
Browser-based FFmpeg holds the whole video in memory while re-encoding, so files near the 200 MB cap (especially long, high-resolution ones) can exhaust a browser tab on machines with little RAM. Trimming the clip first, or processing a shorter section, usually succeeds.