H.264 and H.265 do the same job: make a playable file smaller. The trade-off is size versus who can open it.
Send H.264 if you do not know the other person’s device. Use H.265 when you do, and you need the file smaller.
MP4 is not a codec
A codec compresses the frames. H.264 and H.265 are codecs.
A container is the wrapper — MP4, MOV, MKV, WebM. It can hold a video track, an audio track, and subtitles.
“Convert to MP4” is an incomplete instruction. An MP4 can contain H.264 or H.265. ConvertYard always writes an MP4; the H.265 toggle decides what is inside it.
This is why an iPhone clip sometimes will not play on an older Windows PC. The file is an MP4, but Camera → Formats → High Efficiency recorded HEVC (H.265). Most Compatible records H.264.
How much smaller is H.265, really
At matched visual quality, on the same resolution and frame rate:
| Footage | Typical saving vs H.264 |
|---|---|
| Talking head, lecture, meeting | 35–50% |
| Screen recording, slides, UI | 30–45% |
| Walking / vlog | 30–40% |
| Sport, games | 20–35% |
Already-compressed clips have less left to give. Grain, low light, and fast motion cost bits in either codec. Treat the table as a planning range, not a promise.
The compressor’s quality levels are CRF. The numbers differ by codec — CRF 23 in x264 is not the same knob position as CRF 23 in x265 — so use the named levels:
| Level | H.264 CRF | H.265 CRF | Use |
|---|---|---|---|
| Small | 18 | 22 | Near-lossless. Small size win. |
| Medium | 23 | 26 | Default. Usually the right first try. |
| High | 28 | 30 | Noticeable if you look. Much smaller. |
| Maximum | 35 | 36 | Soft. Previews and archives, not delivery. |
Downscaling still beats a codec change when you do not need the original pixels. A 4K screen recording re-encoded to 720p H.264 is often smaller than 4K H.265, and it plays everywhere.
What actually plays it
H.264 decodes in hardware on essentially every phone, laptop, smart TV, and browser from the last 15 years. First-try compatibility: H.264 in an MP4.
H.265 is fine on current devices and still a gap on older ones:
- iPhone / iPad — hardware decode since iPhone 7. Recent iPhones record HEVC by default.
- Android — hardware decode is normal from about 2016 on. Older than that is the problem set.
- macOS / Safari — native.
- Windows 10 / 11 — only if HEVC extensions are installed. A clean Windows box without them will not play H.265 in every app.
- Chrome / Firefox / Edge — they use the OS decoder. No OS support, no playback.
- 4K TVs — almost all decode HEVC (UHD Blu-ray required it).
A working rule
| Situation | Codec |
|---|---|
| Unknown recipient, client, student, public download | H.264 |
| Form / LMS / portal that says “MP4” | H.264 (they usually mean this) |
| WhatsApp, MMS, old Windows laptop | H.264 |
| You will edit it again in picky software | H.264 |
| Gmail 25 MB and H.264 looks ugly | H.265 |
| Your own archive, modern hardware | H.265 |
| Only recent phones or a current Mac will play it | H.265 |
YouTube and Instagram re-encode on ingest. Picking H.265 will not “beat” their compressor. It can only help you stay under their upload cap. Start from the best source you have. Do not bounce H.264 → H.265 → H.264. Each lossy pass adds damage.
Encode time
H.265 is heavier. In a browser there is no NVENC or VideoToolbox — ConvertYard runs libx265 on CPU with a fast preset.
Same clip, H.265 takes longer than H.264. HandBrake at a slow preset can beat the in-browser file at the same nominal quality because it searches harder. For an email attachment that is rarely why you opened a tab.
If the file already fits the cap as H.264 Medium, leave H.265 off.
How to switch
- Open the video compressor.
- Drop the file.
- Leave H.265 output (HEVC) off for H.264, or turn it on.
- Pick a level, or turn on Target size if you have a hard cap.
- Download the MP4.
Duration does not change. Resolution changes only if you pick 1080p / 720p / 480p / 360p. Audio is copied when the source is already AAC at a bitrate that fits; otherwise it is re-encoded to AAC.
The useful test: take a 20-second slice of your footage, compress it twice at Medium (toggle off, then on), and play both on the device that has to work. That beats any “50% smaller” claim.