MP4 to MP4 Converter
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Supports: MP4, M4V
Advanced Options - Our defaults are optimized for the best results. We recommend you keeping the defaults unless you have a specific need.
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Need help?How to Convert MP4 to MP4
- Upload Your MP4 File — Click "Choose Files" or drag and drop your MP4 or M4V video file. Both extensions are accepted.
- Choose Video Codec — Under Video Codec, the default is H.264. Change to H.265 for better compression or AV1 for maximum efficiency.
- Set Video Quality — Under File Compression, choose from: Quality Preset (Highest through Lowest), Target File Size % (1-100% slider with Smart Scaling), Specific File Size (MB/KB), Constant Bitrate, Variable Bitrate, Constant Quality (CRF), or Constraint Quality.
- Set Audio Codec — Under Audio Codec, the default is AAC.
- Adjust Resolution (Optional) — Under Video Resolution, keep the original or choose Preset Resolutions (4K, 1080p, 720p, etc.), Fixed Resolutions, Resolution Percentage, or custom Width/Height/Width×Height.
- Trim (Optional) — Under Trim, set a Start Time and Duration to extract a specific segment.
- Convert & Download — Click "Convert" and download your re-encoded MP4 file.
Why Convert MP4 to MP4?
Converting MP4 to MP4 re-encodes the file, which is useful for compressing large MP4 files to reduce storage and sharing size, upgrading the codec (e.g., H.264 → H.265 for 50% smaller files), lowering resolution for mobile or web use (e.g., 4K → 1080p), trimming unwanted sections without changing the format, and adjusting bitrate for specific upload limits (email, social media).
Re-encoding Options
| Goal | Recommended Setting |
|---|---|
| Reduce file size by 50% | Target File Size: 50% |
| Fit under 25 MB (email) | Specific File Size: 25 MB |
| Upgrade to H.265 | Change Video Codec to H.265 |
| Lower resolution | Video Resolution: 720p or 480p |
| Extract a clip | Trim: Start Time + Duration |
| Best quality-to-size | Constant Quality (CRF) |
Codec Comparison
| Codec | Compression | Speed | Compatibility |
|---|---|---|---|
| H.264 (default) | Good | Fast | Universal |
| H.265 | ~50% better | Slower | Modern devices (2015+) |
| AV1 | ~30% better than H.265 | Slowest | Newest devices |
Why would I convert MP4 to MP4?
The main use cases are compression (reducing file size), codec upgrade (H.264→H.265), resolution change (4K→1080p), and trimming. The output stays in the universally compatible MP4 format.
Will re-encoding reduce quality?
Yes, some quality loss is inherent. Use Quality Preset "Highest" or Constant Quality (CRF) with a low value to minimize visible degradation. The trade-off is smaller file size.
How much can I reduce the file size?
Target File Size at 50% produces roughly half the original size. Upgrading from H.264 to H.265 saves an additional 40-50%. Combining codec upgrade with resolution reduction can achieve 70-90% reduction.
Can I trim and compress at the same time?
Yes. Set trim points under Trim, then choose a compression method under File Compression. Both are applied in a single pass.
What is the difference between CRF and Target File Size?
CRF maintains consistent visual quality — you control quality, the encoder determines file size. Target File Size lets you specify the exact output size — the encoder adjusts quality to hit your target.