Resize Video Online
Shrink or enlarge your clip by percentage and see the new resolution and estimated file size before you export. Processed locally in your browser - no upload, no watermark.
This tool resizes by percentage, so width and height change together. Your video keeps its original aspect ratio, which helps avoid the stretched faces, oval circles and black-bar surprises that happen when a clip is forced into the wrong shape.
Use Resize when you want the same frame, just smaller or larger. If you need a vertical clip for Reels, a square post, a 16:9 canvas or a manual crop, open the file in GrepCut Studio instead.
A smaller frame has fewer pixels per video frame, so the encoder has less visual information to store. That is why scaling down can make your file easier to upload to chat apps, email, course portals or social platforms.
The estimate is based on pixel count, so it is useful for choosing a scale before you export. The final file can still vary because motion, audio, source compression and encoder settings all affect the finished MP4.
Resize runs in your browser, so your file is not uploaded to a server. That matters when your clip contains private footage, client material, a class recording or a large file that would be slow to send anywhere first.
Because the work happens locally, performance depends on your computer or phone. Large 4K files need more memory, and export speed depends on browser support and hardware-accelerated encoding where available.
Can you resize a video without uploading it?
Yes. Your video is processed in your browser, so it stays on your device. You only download the new MP4 when you export.
Will resizing make your video file smaller?
Scaling down often makes the file smaller because the output has fewer pixels per frame. The exact size still depends on motion, audio and how the browser encodes the MP4.
Will your video get stretched?
No. Resize scales width and height by the same percentage, so the original aspect ratio is preserved.
Can you resize a 4K video to 1080p?
Yes, if the percentage you pick lands near that target. For example, 50% turns a 3840 × 2160 clip into 1920 × 1080.
Can you change a landscape video into vertical video here?
Not with percentage resize alone. Use [Crop Video](/tools/crop-video) or GrepCut Studio when you need a 9:16, 1:1 or custom canvas.
Does 200% or 400% upscaling improve quality?
It makes the frame larger, but it does not recreate detail that was missing in the source. If the original is blurry or heavily compressed, the bigger export may still look soft.
Why is the exported file size different from the estimate?
The estimate is based on the resolution change. Real output size can shift because video content, audio, source compression and browser encoding all affect the final MP4.
What format do you get back?
You get a standard MP4 using H.264 video, designed for broad playback and clean uploads across common platforms.