Video Resizer
Change video dimensions to 1080p, 720p, 480p, or custom pixel values directly in your browser. Lock aspect ratio to prevent stretching without uploading data.
MP4, WebM, MOV, MKV, AVI, FLV, 3GP · up to 1 GB
Tips
- Keep the aspect ratio locked so your video frame does not stretch or distort horizontally or vertically.
- Downscaling saves bandwidth and storage, but upscaling a low-resolution clip will not restore missing detail.
- The processing engine downloads roughly 30 MB on your first visit and runs offline on subsequent uses.
How to use it
- 1 Select or drag and drop your video file into the designated area.
- 2 Pick a standard target resolution preset or enter custom pixel dimensions with aspect ratio lock enabled.
- 3 Start the conversion process and keep the tab open while the browser encodes your video.
- 4 Save the resized video file directly to your local storage once processing finishes.
What you should know
Downscaling video resolution is essential when reducing payload sizes for web embeds, email attachments, or mobile delivery. High-definition 4K and 1080p source files demand heavy bandwidth and decoding power. Lowering the display resolution to 720p or 480p drastically cuts pixel counts—dropping from 1080p to 720p eliminates over half the pixels per frame—which allows the encoder to use lower bitrates without aggressive compression artifacts. Maintaining the source aspect ratio prevents geometric distortion across target devices. Upscaling, by contrast, only inflates file size through spatial interpolation without recovering actual visual data.
This tool resizes MP4 and other video streams directly in your browser using client-side WebAssembly, meaning your video data never leaves your machine. Choose standard resolution presets like 1080p, 720p, and 480p, or input custom width and height values while keeping aspect proportions intact. Resizing re-encodes the visual stream, which discards non-standard metadata tracks but preserves primary audio channels. Because processing runs single-threaded inside the active browser tab, encoding times scale with video duration and frame complexity. Leave the tab open until the exported file is ready for download.
Measured output sizes
Test clip: a 10-second, 1280×720 H.264 MP4 without an audio track (4.8 MB, animated film footage). Run on the live tool in Chrome 154 on a desktop PC with the video engine already loaded; on a first visit add a one-time download of about 30 MB. Output format MP4, height left empty so the aspect ratio follows the width.
| Target width | Output | Quality | File size | Change | Time to encode |
|---|---|---|---|---|---|
| 1280 px | 1280×720 | Balanced (23) | 2.3 MB | −52% | 18 s |
| 960 px | 960×540 | Balanced (23) | 1.3 MB | −73% | 13 s |
| 854 px | 854×480 | Balanced (23) | 1.1 MB | −77% | 11 s |
| 640 px | 640×360 | Balanced (23) | 691 KB | −86% | 7 s |
| 426 px | 426×240 | Balanced (23) | 365 KB | −93% | 5 s |
| 640 px | 640×360 | High (18) | 1.6 MB | −66% | 8 s |
| 640 px | 640×360 | Small (28) | 279 KB | −94% | 7 s |
| 640 px | 640×360 | Smallest (32) | 145 KB | −97% | 7 s |
- Even keeping the width at 1280 px halved the file, to 2.3 MB, because the clip is re-encoded at the Balanced setting rather than copied.
- Each step down the ladder costs roughly half again: 1.3 MB at 960 px, 691 KB at 640 px, 365 KB at 426 px.
- At a fixed 640×360 the quality chips span a factor of eleven, from 1.6 MB at High (18) to 145 KB at Smallest (32). Resolution and quality are worth setting together.
- Encoding this 10-second clip stayed under 20 seconds and got quicker as the frame shrank: 18 seconds at 1280 px, 5 seconds at 426 px.
Frequently asked questions
Why does resizing a video take longer than processing an image?
Video resizing requires decoding, scaling, and re-encoding thousands of individual frames sequentially. Because the WebAssembly engine runs on a single CPU thread in your browser, processing lengthy or high-framerate clips takes noticeable time.
Will downscaling a video decrease its visual quality?
Downscaling reduces the total pixel grid, which softens fine details when viewed on larger displays. However, it significantly reduces file size and playback stutter without introducing blocky compression noise if bitrate parameters remain balanced.
Are my video clips uploaded to a remote server for processing?
No, all video scaling and re-encoding happen locally inside your browser tab using WebAssembly. Your media files are never transferred over the internet or stored on external servers.
Guides
Articles and format references related to this tool.
- Free Video to GIF Converter: MP4, MOV & WebM to GIF 10 September 2026
- Free GIF to MP4 Converter: Turn Animated GIFs into Video 21 September 2026
- How to Convert Video Files for Any Device or Platform 9 September 2026
- What is an MP4 file? A container for H.264, H.265 or AV1 video with AAC audio
- What is a WebM file? A container for VP8/VP9/AV1 video with Vorbis or Opus audio
Related tools
- Video Compressor Compress videos to a target file size or custom quality in your browser. Re-encode offline without uploading footage to external servers or losing privacy.
- Video Merger Combine multiple video clips into a single file in your browser. Reorder tracks, match frame rates automatically, and merge footage without server uploads.
- Video Cutter Trim video clips by selecting start and end timestamps. Choose instant stream copy or frame-accurate re-encoding with full privacy right inside your browser.
- AVI to MP4 Converter Convert legacy AVI videos into universal MP4 files right in your browser. Re-encode video using H.264 compression without uploading files to any server.
- FLV to MP4 Converter Convert legacy Flash FLV video files to modern MP4 format. Adjust video quality and resolution locally in your browser without uploading files to any server.