# HEVC / H.265 vs H.264: Differences, Compatibility, and When to Use Each
**HEVC** (High Efficiency Video Coding), also known as **H.265**, is the successor to H.264/AVC. It promises the same visual quality at roughly half the file size. But "half the size" comes at a cost: higher CPU load and more limited compatibility.
## What is HEVC / H.265
H.265 is a video compression standard developed by the JCT-VC (Joint Collaborative Team on Video Coding), published in 2013. Its improvements over H.264 include:
- **Larger prediction blocks**: up to 64×64 px (H.264 maxes at 16×16), better for 4K content
- **More prediction modes**: more accurate intra/inter prediction → fewer bits for the same detail
- **Larger transform sizes**: DCT up to 32×32 (H.264 max is 8×8)
- **Result**: same PSNR with ~40–50% less bitrate
## H.264 vs H.265 comparison
| Aspect | H.264 / AVC | H.265 / HEVC |
|--------|-------------|--------------|
| Published | 2003 | 2013 |
| File size | Reference | ~40–50% smaller than H.264 |
| Quality at equal bitrate | Reference | Better (especially 4K) |
| CPU load (encoding) | Medium | High (2–5× more) |
| CPU load (decoding) | Low | Medium-high |
| Hardware decoding | Universal | Modern devices (2017+) |
| Compatibility | Universal | Good (with some limitations) |
| Patent licensing | Complex, free in many cases | Complex, some decoders charge fees |
## How much better is HEVC really?
In practice, gains vary by content type:
| Content | Bitrate savings with HEVC |
|---------|--------------------------|
| 4K video (high detail) | 45–55% |
| 1080p film | 35–45% |
| Animation / anime | 30–40% |
| Gaming (fast motion) | 20–30% |
| Screen recordings | 40–50% |
## Compatibility: H.265's Achilles heel
HEVC has a partial adoption problem:
**Natively supported:**
- Windows 10/11 (with HEVC extension from Microsoft Store, ~$0.99)
- macOS 10.13 High Sierra and later
- iOS 11+ / Android 5+
- Modern players (VLC, mpv, MPC-HC)
- Smart TVs manufactured from 2016–2018 onward
- PS5, Xbox Series X
**Problem areas:**
- Windows 10 without the paid extension can't play HEVC natively
- Web browsers: Chrome and Firefox don't support HEVC in native HTML5 video (they use AV1 or VP9 instead)
## H.265 vs AV1 vs VP9
The modern codec landscape:
| Codec | Size vs H.264 | Compatibility | Encoding speed |
|-------|--------------|---------------|----------------|
| H.264 | Reference | Universal | Fast |
| H.265 | −40% | Good | Slow |
| VP9 | −30% | Very good (Chrome, Firefox, Android) | Slow |
| AV1 | −50% | Growing (Chrome, Firefox, Android 10+) | Very slow |
| H.266/VVC | −50% vs H.265 | Minimal (2020, early adoption) | Extremely slow |
AV1 is HEVC's most serious competitor because it's royalty-free.
## When to use H.265
**Use H.265 when:**
- Recording or storing 4K/8K video — the storage savings are significant
- Your target device has HEVC hardware decoding (iPhone 6s+, modern Android, Apple TV 4K)
- Long-term archiving and you want to minimize storage space
- Streaming over slow networks where every MB matters
**Use H.264 when:**
- Web distribution (YouTube, Vimeo, Facebook) — they re-encode anyway
- You need maximum compatibility with older devices
- Encoding speed is critical (H.264 is much faster)
- Video editing in a DAW — most software handles H.264 better
## Convert H.264 to H.265 with FFmpeg
```bash
# Basic HEVC conversion with reasonable quality (CRF 28 ≈ visual quality of H.264 CRF 23)
ffmpeg -i video_h264.mp4 -c:v libx265 -crf 28 -c:a copy video_h265.mp4
# With preset (ultrafast=less compression, veryslow=maximum compression)
ffmpeg -i video_h264.mp4 -c:v libx265 -crf 28 -preset slow -c:a copy video_h265.mp4
# Preserve audio and subtitles
ffmpeg -i video.mkv -c:v libx265 -crf 28 -c:a aac -b:a 128k video_h265.mkv
```
Recommended CRF range for HEVC: 24–28. Lower = higher quality and size; higher = lower quality and size.
## Conclusion
H.265 delivers genuine, meaningful storage savings — especially for 4K. However, its more limited compatibility (particularly in web browsers) means H.264 remains the standard for general distribution. For archiving and streaming over bandwidth-constrained networks, HEVC is the right choice.
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