How does video resizing work?

Our tool re-encodes your video at the target dimensions using WebCodecs in your browser. You choose how the video fits the new frame: crop to fill, letterbox to preserve everything, or stretch to match exactly.

Is my video uploaded to a server?

No. All processing happens entirely in your browser using WebCodecs technology. Your video never leaves your device, making this the most private video resizer available.

Which video formats are supported?

MP4, MOV, AVI, WebM, and MKV input files are supported. The output is always MP4 (H.264) for maximum compatibility across all devices and platforms.

What is the difference between crop, letterbox, and stretch?

Crop (cover) fills the target frame and trims overflow edges. Letterbox (contain) fits the entire video inside the frame, adding black bars where needed. Stretch (fill) deforms the video to exactly match the target dimensions.

Can I resize a vertical video to landscape?

Yes. Upload your 9:16 vertical video and select a 16:9 landscape preset. Choose Crop to fill the frame (top/bottom trimmed), Letterbox to show the full video with side bars, or Stretch to fill completely.

Free Tool

Resize Video Online — Free, No Watermark

Resize videos for any platform or aspect ratio. Your video never leaves your browser.

No UploadNo Watermark100% PrivateFree Forever

Drag & drop your video or click to browse

Supports MP4, MOV, AVI, WebM, MKV

No Server Upload No Watermark 100% Private Free Forever

How to Resize a Video Online

Upload Your Video

Drag and drop any video file (MP4, MOV, AVI, WebM). No file size limit — processing happens on your device.

Choose Size & Fit Mode

Pick an aspect ratio preset, select a platform like TikTok or YouTube, or enter custom dimensions. Choose crop, letterbox, or stretch.

Download Resized Video

Your resized video is ready in seconds. No watermark is added. Click download to save.

Why Use Our Video Resizer?

Client-Side Processing

Your video is resized in your browser using WebCodecs. Nothing is uploaded to any server. This is faster, more private, and works even on slow internet.

No Watermark, Ever

Unlike other tools, we don't stamp watermarks on your exports. Free means genuinely free.

Platform Presets

One-click presets for TikTok, Instagram Reels, YouTube Shorts, LinkedIn, and more. Get the exact dimensions every platform needs without looking them up.

Resize Video for Any Platform

Frequently Asked Questions

Need more than resizing? Our full video editor has keyframes, animations, captions, and AI tools.

Try the Editor

Our free online video resizer uses modern WebCodecs technology to resize video files directly in your web browser. Unlike traditional online video resizers that upload your files to remote servers, our tool processes everything locally on your device. This means your videos remain completely private — they never leave your computer. The resizer supports all major video formats including MP4, MOV, AVI, WebM, and MKV, and outputs universally compatible MP4 files encoded with H.264. Whether you need to resize a video for TikTok's 1080x1920 vertical format, convert a landscape video to Instagram Reels' 9:16 aspect ratio, create a square video for Instagram posts, or prepare content for YouTube, LinkedIn, or Twitter/X, our platform preset buttons set the exact dimensions automatically. The resizer offers three fit modes to control how your content fills the new frame: Crop (cover) fills the target dimensions and trims overflow, ideal for platform-native content. Letterbox (contain) fits the entire video inside the frame with black bars, preserving all content. Stretch (fill) deforms the video to exactly match the target dimensions. Each mode serves different creative needs, giving you full control over the final output without complex video editing software.