Resize MP4 Online
Change an MP4 to 720p, 1080p, or a smaller width.
About Resize MP4 Online
Resize MP4 online without installing desktop software. This page opens the same server-side resize tool used by our general video resizer, with 720 px selected as the starting width. Upload an MP4, MOV, WEBM, MKV, or AVI file, choose a width, and the encoder scales the frame while keeping the audio track. The result is a standard H.264 MP4 that plays in browsers, phones, and presentation software. Each upload runs in a temporary job folder and is deleted within 15 minutes. The 100 MB input limit keeps jobs predictable; for longer recordings, trim the clip first with Video Cutter.
How to Use Resize MP4 Online
Upload your video
Drag an MP4 into the upload area or click to choose a file from your device. MOV, WEBM, MKV, and AVI files also work, and the upload limit is 100 MB.
Pick a width
Choose 240, 360, 480, 720, or 1080 px. The height follows the source aspect ratio and is rounded to an even number so H.264 encoding stays compatible. 720 px is selected by default on this page.
Resize the video
Click Resize video. The server scales the frame and re-encodes it as H.264 video with AAC audio. A short clip usually finishes in under a minute; longer files take more time.
Preview and download
Play the result in the preview player, check captions, faces, and fine text, then download the MP4. If the frame looks soft, go back and choose a larger width before encoding again.
Common Use Cases
Uploading to sites with width limits
Some learning portals, support desks, and social schedulers reject oversized frames or take too long to process 4K files. A 720 px or 1080 px MP4 is easier to upload and review.
Sending clips to older devices
Projectors, older phones, and in-car players often handle 720p more smoothly than 4K footage. Resizing gives the device a frame size it can decode without stutter.
Reducing size before messaging
A narrower frame lowers the bitrate the encoder needs, so the finished MP4 is usually smaller. For a stricter size cap, send the resized file through Compress Video afterward.
Technical Specifications
| Input Formats | MP4, MOV, WEBM, MKV, AVI |
|---|---|
| Output Formats | MP4 |
| File Size Limit | 100 MB |
| Processing Engine | Dedicated secure server worker |
| Data Retention | 15 minutes |
| Batch Processing | Single file processing |
Tips for Best Results
Resize before you compress when a platform enforces both a resolution and a file size cap. Starting with a smaller frame gives the compressor less data to carry.
Do not upscale a 480p clip to 1080p just to match a form. Upscaling adds pixels but not detail, and the file grows without looking sharper.
If the source is longer than you need, cut the useful section with Video Cutter before resizing. A shorter clip finishes faster and produces a smaller file.
Frequently Asked Questions
Does resizing an MP4 reduce quality?
The tool re-encodes the video, so some detail is discarded. The loss is usually hard to see when you resize down to 720p or 480p. Choose a width at or below the source width, and keep the output at 1080p when the source is 1080p or higher.
Which widths can I choose?
This page offers 240, 360, 480, 720, and 1080 px. The height is calculated from the original aspect ratio and rounded to an even number. Portrait videos stay portrait because only the width is fixed.
What happens to the audio track?
The audio track is kept and encoded as AAC at 128 kbps. If the source has no audio, the output still plays normally; the encoder simply writes a video-only MP4.
What is the maximum MP4 upload size?
Uploads are limited to 100 MB. For a larger file, trim it with Video Cutter first, or compress it with Compress Video before resizing.
Can I resize a portrait video recorded on a phone?
Yes. Phone videos are commonly stored as landscape frames with rotation metadata. The resizer scales the stored frame and the output keeps the same orientation, so a vertical clip remains vertical.
Why is the result still an MP4?
MP4 with H.264 video and AAC audio plays on the widest range of browsers, phones, and TVs. Keeping one output format avoids compatibility problems after resizing.