MP4 Video File Size Calculator
File Size (MB) = (Bitrate × Duration × 60) ÷ 8192(Assuming 1 Byte = 8 bits, and 1 MB = 1024 KB)
MP4 has become one of the most common video file formats due to its excellent balance of compression and quality, wide compatibility, and streaming efficiency. However, estimating or understanding the MP4 file size can be tricky because it depends on various parameters like bitrate, resolution, compression codec, frame rate, and duration.
In this comprehensive blog post, you will learn how to calculate MP4 video file size, how key factors influence it, and practical tips for managing file size without sacrificing quality. Plus, you'll find easy-to-use formulas, explanation tables, and real-world examples to master MP4 file size estimation.
1. What Is MP4?
MP4 (MPEG-4 Part 14, file extension .mp4) is a digital multimedia container format primarily used for storing video and audio data, subtitles, and images. MP4 is popular because:
- Supports various codecs (H.264, H.265, AAC audio, etc.)
- Good compression ratio balancing quality & size
- Broad device and software compatibility
2. Core Factors Influencing MP4 File Size
| Factor | Description |
|---|---|
| Bitrate | Amount of data processed per second (usually in Mbps). The most critical factor affecting size and quality. |
| Duration | Length of the video (in seconds). Longer videos lead to larger files. |
| Resolution | Number of pixels (e.g., 1920x1080 for Full HD, 3840x2160 for 4K). Higher resolution means more pixels to encode, larger file size without compression. |
| Frame Rate | Frames per second (fps), e.g., 24, 30, 60 fps. Higher fps usually means more data per second. |
| Codec | Compression algorithm used (e.g., H.264, H.265). More advanced codecs can maintain quality with smaller files. |
| Compression Settings | Quality parameters such as Constant Rate Factor (CRF) or variable bitrate encoding affect file size. |
3. The Basic MP4 File Size Calculation Formula
The most straightforward way to estimate MP4 video file size is:File Size (MB)=Bitrate (Mbps)×Duration (seconds)8File Size (MB)=8Bitrate (Mbps)×Duration (seconds)
Why divide by 8?
Because bitrate is in megabits per second (Mbps), but file size is measured in megabytes (MB), and 1 byte = 8 bits.
Example:
For a 5-minute (300 seconds) video encoded at 8 Mbps:8×3008=300 MB88×300=300MB
So, approximately, the file will be 300 MB.
4. Bitrate and Its Impact on MP4 File Size and Quality
| Bitrate (Mbps) | Expected Quality | Expected Use Case | Approx. File Size per Minute (MB) |
|---|---|---|---|
| 1 - 2 | Low quality, mobile streaming | Social media clips, small devices | 7.5 - 15 MB |
| 3 - 5 | Good quality, 720p HD streaming | YouTube, casual viewing | 22.5 - 37.5 MB |
| 8 - 12 | Very good quality, 1080p Full HD | Standard YouTube HD, Vimeo | 60 - 90 MB |
| 15 - 25 | Excellent quality, 4K streaming | Netflix, professional 4K production | 112.5 - 187.5 MB |
| 50+ | Raw-like or very high quality | Archive masters, professional editing | ~375 MB and above |
Note: Higher bitrate means higher quality but exponentially larger file sizes.
5. How Resolution Affects Size
The resolution determines the number of pixels, which directly impacts bitrate requirements to maintain quality.
| Resolution | Pixel Count | Approximate Minimum Bitrate for Good Quality (Mbps) |
|---|---|---|
| 480p (SD) | 854 × 480 ≈ 0.41 MP | 1 - 2 |
| 720p (HD) | 1280 × 720 ≈ 0.92 MP | 3 - 5 |
| 1080p (Full HD) | 1920 × 1080 ≈ 2.07 MP | 6 - 12 |
| 1440p (2K) | 2560 × 1440 ≈ 3.7 MP | 10 - 20 |
| 2160p (4K UHD) | 3840 × 2160 ≈ 8.3 MP | 15 - 50+ |
MP = megapixels
Higher resolution demands higher bitrates to avoid compression artifacts, increasing file size.
6. Frame Rate's Role in File Size
- Standard video frame rates: 24, 25 fps (movies/TV), 30 fps (web video), 60 fps (gaming and high-motion content).
- Higher fps means more frames per second → more data to encode → bigger files.
7. Codec and Compression: The File Size Game Changers
| Codec | Compression Efficiency | Typical Usage | Bitrate Compression (Compared to H.264) | Notes |
|---|---|---|---|---|
| H.264 (AVC) | Good | Most devices, platforms | Baseline | Balances quality and compatibility |
| H.265 (HEVC) | Better (~50% less than H.264) | 4K streaming, UHD Blu-ray | ~50% less | Complex encoding, needs support |
| VP9 | Similar or better than H.265 | YouTube, WebRTC | ~50% less | Open source, slower encoding |
| AV1 | Most efficient but new | Emerging streaming codecs | ~30-50% better than H.265 | Yet to be supported widely |
Using H.265 instead of H.264, you can roughly halve file size for same quality, important with 4K and higher resolutions.
8. Audio Bitrate and Size Impact
Audio typically takes far less data than video but still affects total file size.
| Audio Bitrate | Approximate Size per Minute (MB) | Typical Use |
|---|---|---|
| 96 kbps | 0.72 MB | Voice, podcasts |
| 128 kbps | 0.96 MB | Typical MP3 audio, streaming |
| 192 kbps | 1.44 MB | Higher quality music |
| 320 kbps | 2.4 MB | Near CD-quality audio |
Example: A video with 5 Mbps video bitrate and 128 kbps audio will have:
- Total bitrate = 5 + 0.128 = 5.128 Mbps
- File size accordingly slightly larger than video-only.
9. MP4 File Size Calculator Table
| Duration (Min) | Bitrate (Mbps) | Estimated File Size (MB) | Estimated File Size (GB) |
|---|---|---|---|
| 1 | 2 | 15 | 0.015 |
| 5 | 4 | 150 | 0.15 |
| 10 | 8 | 600 | 0.6 |
| 30 | 10 | 2250 | 2.25 |
| 60 | 20 | 9000 | 9 |
10. Real-World Examples
| Platform | Resolution & Codec | Typical Bitrate (Mbps) | File Size Estimate per Hour | Notes |
|---|---|---|---|---|
| YouTube | 1080p H.264 | 8 | ~3.6 GB | Adaptive streaming |
| Netflix | 4K H.265 (HEVC) HDR | 15-25 | 7-11 GB | High quality streaming |
| iPhone Default | 4K H.264/HEVC, 30fps | 44 | ~20 GB | High-quality personal videos |
| Vimeo Pro | 1080p H.264 | 7.5 | ~3.4 GB | Professional upload |
11. Tips to Manage MP4 File Size Without Sacrificing Quality
- Use hardware-accelerated codecs (H.265) when possible.
- Choose appropriate bitrate matching your resolution and fps.
- Employ variable bitrate (VBR) encoding to optimize complex vs simple scenes.
- Keep audio bitrate optimal — avoid unnecessarily high audio bitrates.
- Trim unneeded footage or segments.
- Use two-pass encoding for better bitrate distribution.
- Consider reducing frame rate if frame-for-frame fidelity is not needed.
12. Summary Formula and Conversion Reference
| Step | Formula / Info |
|---|---|
| Convert bitrate to byte rate | Divide Mbps by 8 |
| Calculate file size (MB) | Byte rate (MB/s) × Duration (s) |
| Convert MB to GB | Divide MB by 1024 |
| Example for 5 Mbps, 60 seconds | (5 / 8) × 60 = 37.5 MB |
Conclusion
MP4 file size depends chiefly on bitrate and duration, with important roles from resolution, frame rate, codec, and audio settings. The simple formula:
File Size (MB) = Bitrate (Mbps)/8 × Duration (seconds)
offers a starting point for quick calculations. Incorporating codec choice and compression characteristics will refine your estimates.
By using this knowledge and tables, you can optimize video workflows, plan storage and bandwidth effectively, and tailor quality vs size for your needs.