How to use it
- Drop your video onto the page.
- Pick an aspect ratio: original, 16:9, 9:16, 1:1 or 4:5.
- Pick a resolution for the shorter side.
- Choose bars or crop, then click Resize video.
Resolution
The resolution setting sets the shorter side of the output, so it works the same for landscape and portrait videos: 720p means 1280×720 for a landscape clip and 720×1280 for a vertical one. Choose original, 1080p, 720p, 540p, 480p or 360p.
Scaling down is the main use: a 4K phone video resized to 1080p or 720p plays smoothly on any device and is much easier to share. You can also scale up, but the tool reminds you that the video only gets bigger, not sharper. Dimensions are rounded to even numbers, which H.264 requires.
Aspect ratio for social media
| Aspect ratio | Common use | Example at 1080p |
|---|---|---|
| 16:9 | YouTube, TVs, laptops | 1920×1080 |
| 9:16 | Reels, TikTok, YouTube Shorts, Stories | 1080×1920 |
| 1:1 | Square feed posts | 1080×1080 |
| 4:5 | Instagram portrait feed posts | 1080×1350 |
When the new ratio differs from the original, choose how to fit the picture:
- Black bars (everything visible): the whole picture is kept and the empty space is filled with black, like letterboxing.
- Crop to fill: the picture fills the frame and the edges that stick out are cut off, centered.
A small diagram shows how your video will sit in the new frame before you start.
Which resolution to pick
| Resolution | Landscape size | Good for |
|---|---|---|
| 1080p | 1920×1080 | Full HD playback, YouTube, social posts |
| 720p | 1280×720 | Messaging, email, websites, smaller files |
| 540p | 960×540 | Phone viewing with small files |
| 480p | 854×480 | Previews, slow connections |
| 360p | 640×360 | Thumbnails, the smallest usable size |
Most social platforms recompress whatever you upload, so uploading at the platform's own maximum (often 1080p) gives the cleanest result. For sharing in chat apps, 720p is usually the sweet spot between sharpness and size.
Quality and speed
Resizing re-encodes the video as H.264 MP4 with light compression, at a bitrate matched to the new resolution, and never above the original's when you keep the original aspect ratio. Audio is kept and converted only if MP4 can't hold its format. Encoding uses your device's hardware-accelerated video engine, so a short phone clip usually takes seconds; long or 4K videos can take several minutes.
The file is named after the original with the new size added, for example beach-1080x1920.mp4.
Tips
- For Reels and TikTok, horizontal footage cropped to 9:16 keeps only the center third of the picture; make sure the action is in the middle, or use black bars instead.
- For a smaller file without changing the shape, keep the original ratio and pick 720p.
- To make a file as small as possible, use the video compressor, which also offers a target size in MB.
- To fix a sideways video first, rotate it.
Your video is processed in your browser and never uploaded. It works in current Chrome and Edge, Safari 16.4 or later and Firefox 130 or later on desktop.
Frequently asked questions
How do I resize a video for Instagram Reels or TikTok?
Choose the 9:16 aspect ratio and 1080p, then pick black bars or crop to fill, and click Resize video.
How do I change a video from 4K to 1080p?
Keep the original aspect ratio, choose 1080p and click Resize video.
Will resizing reduce quality?
Scaling down always discards detail, but the result looks sharp at its new size. Light compression is used to keep quality high.
Can I make a vertical video horizontal?
Yes. Choose 16:9; with black bars you get a pillarboxed video, with crop to fill the top and bottom are cut off.
Is my video uploaded?
No. Resizing happens entirely in your browser.
Last updated: November 12, 2026