How to Compress a Video File Size on Your Phone | What to Do When It Won't Send
Have you ever tried to send a video you shot on your phone over LINE or email, only to see "the file is too large"? This article explains how to shrink a video's file size using only your phone — no computer required — with resolution guidelines for different purposes.
Why Video Files Get So Large
A video's file size is determined mainly by three factors: resolution, bitrate, and length. Since most phones now shoot in Full HD (1080p) or 4K by default, it's not unusual for even a few minutes of footage to exceed several hundred MB or even 1GB. Because LINE and email both cap the file size you can send, trying to send high-quality footage as-is often gets rejected.
Three Ways to Compress a Video
1. Let the sending app auto-compress it
Apps like LINE will automatically lower the quality somewhat when you send a video, but you can't control how much it compresses, and the result can end up grainier than you'd like.
2. Re-export it with video editing software on a computer
This lets you fine-tune resolution and bitrate, but it requires transferring the file to a computer and operating editing software, so it's not something you can do quickly while out and about.
3. Convert it by specifying the resolution in a phone app
The easiest option is to convert the video to MP4 with a phone app by specifying the output resolution. Everything happens right on your phone, and the whole process takes just a few taps.
Steps to Compress a Video with MediaToolbox
- Open the app and select "Resize Video"
- Pick the video you want to compress
- Choose an output resolution: 1080p, 720p, or 360p
- Tap "Convert & Save" and you're done
The lower the resolution, the smaller the file size. The key is choosing the right resolution for your purpose.
Resolution Guidelines by Purpose
| Purpose | Recommended resolution | Notes |
|---|---|---|
| Sending quickly via LINE or email | 360p–720p | Prioritizes file size; quality will be somewhat grainier |
| Posting to social media | 720p | Plenty of quality for viewing on small screens |
| Keeping for later viewing | 1080p | Prioritizes quality while still being lighter than the original 4K |
What Else MediaToolbox Can Do
Beyond resizing video, MediaToolbox also handles free-form image resizing and conversion between JPEG/PNG/WEBP, extracting audio from video as M4A, and converting between PDF and images (PDF → images, images → PDF). It's a single app that covers all your video, image, audio, and PDF conversion needs.
MediaToolbox
A simple all-in-one multimedia conversion tool for video, images, audio, and PDFs. Free, with English support.
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