Resize Video
Resize Video changes a clip's dimensions to an exact resolution or a ready-made social-media preset — square for Instagram, vertical for Stories and Reels, widescreen for YouTube. Choose how the frame should fit and export a perfectly sized video without uploading it anywhere.
Add your video
The file is read by your browser and stays on your device — there is no upload step.
Your video
The work runs in this tab. Nothing is sent anywhere, and the download is generated locally.
How to use Resize Video
- 01Upload
Load your video
Drop the file in; its source resolution is detected automatically.
- 02Customize
Choose a size
Pick a preset like 1080p, Square or Vertical, or type a custom width and height.
- 03Process
Pick a fit and export
Choose Fit, Fill or Stretch, then export your resized clip.
What are you resizing for?
Pick the resolution the platform actually plays at. Sending more than it will use costs export time and nothing else.
- Reels, TikTok, Shorts1080 × 1920
Full-screen vertical 9:16. Anything wider gets pillarboxed or cropped by the app's own framing.
- Instagram feed1080 × 1080
Square 1:1. The grid preview crops to square anyway, so composing for it avoids surprises.
- YouTube1920 × 1080
Standard 16:9 at 1080p. Uploading 4K helps only if the source really is 4K.
- Email or chat1280 × 720
720p roughly quarters the pixel count against 1080p, which is usually the difference between over and under an attachment limit.
- Embedded on a page1280 × 720
Most in-page players are under 900px wide. 720p is already more than they display.
- Archive or re-editkeep the source size
Resizing is destructive. Keep the original resolution for anything you will edit again.
Resize, or something else?
Resizing changes how many pixels the frame is made of; everything in the picture stays in the picture. That is a different job from the ones below.
- The file is too large to sendCompress Video
- I want to choose which part of the frame survivesCrop Video
- It was shot sidewaysRotate Video
- It will not play on the device I need it onConvert Video
- Only part of the clip is worth keepingTrim Video
Fit, Fill or Stretch?
Changing shape — 16:9 landscape into 9:16 vertical, say — means deciding what happens to the part that no longer fits.
Keeps the entire frame and adds black bars to pad it out. Use it when losing part of the image would be worse than the bars — a wide shot where the edges carry the meaning.
Keeps the height and crops the sides away so the frame is covered edge to edge. Use it when filling the screen matters more than the edges. The centre wins by default, which is not always where the subject is.
Forces the source to the exact dimensions and distorts it. Faces are the giveaway. It exists for the rare case where a spec demands exact numbers and the content can survive it.
Shrinking and enlarging are not the same operation
Scaling a video down and scaling it up are not symmetrical.
Downscaling averages several source pixels into each output pixel. Nothing is invented, detail holds up, and the file gets substantially smaller because there are fewer pixels to encode — 1080p to 720p is roughly half the pixels.
Upscaling has to invent pixels that were never recorded, by interpolating between the ones that were. The result is softer and often larger on disk than the original, because the encoder now has more pixels to describe and no more real detail to describe with. Going 720p to 1080p will not recover anything.
Supported formats
- MP4
- MOV
- WebM
- AVI
- MKV
- Maximum file size —
- bounded by your device's memory
- Processed by —
- FFmpeg (WebAssembly), on your device
Your file, and what the page does
Your file is never uploaded. Resize Video reads it into this browser tab and processes it with FFmpeg compiled to WebAssembly on your own device. There is no upload endpoint in the application and no copy on any server — closing the tab discards it.
That is also why processing takes longer here than on a site that uploads: your device is doing the work rather than a rack of servers. The trade is that the file never leaves it.
What the page does send or fetch
- The processing engine, once
- The first time you use any video or audio tool, the browser downloads the FFmpeg WebAssembly build (~30MB) from the jsDelivr CDN and reuses the cached copy afterwards. That is a file coming to you — no part of your own file is in the request.
- Ads on the page
- The site is funded by advertising, so the page loads Google AdSense. That carries the usual web basics — IP address, browser, referring page — as on any ad-supported site.
- An anonymous usage counter
- When Resize Video finishes we record that the tool ran, whether it succeeded and how long it took. No file data, no identifier, no cookie.
Your file is not on that list. How this works.
Frequently asked questions
Fit letterboxes the whole frame inside your size; Fill crops the edges to cover it completely; Stretch distorts to the exact dimensions.
Use Square (1:1) for a feed post and Vertical (9:16) for Stories, Reels and TikTok.
Yes — enter any width and height and the tool renders your video at exactly that size.
Yes — Resize Video is completely free. There's no account, sign-up, watermark or limit.
No. It runs in any modern browser — Chrome, Edge, Safari, Firefox, Brave — with nothing to download or install.
Not sure resizing is what you need?
Start from what is actually wrong with the clip.
- Too large for an upload or attachment limitCompress Video
- Wrong resolution for the platformResize Video
- Wrong part of the frame is in shotCrop Video
- Filmed sideways or upside downRotate Video
- Too long — only a section is neededTrim Video
Edit any media with a right-click
Add Dexta Studio to Chrome and open any image, video, audio or PDF straight into the right tool — free, nothing uploaded.