ProRes and H.264: which one your Mac should be storing

Q: Does converting ProRes to HEVC lose quality?

Some, in principle. At -crf 20 it is very hard to see. If you might grade the footage again, keep the ProRes; if you are watching it, convert.

23 August 2026 · 6 min read

A drive fills up and the cause turns out to be a folder of ProRes exports nobody needed in that format. This happens often, because ProRes is offered as a quality option and reads as the better choice, and the storage consequence is not stated anywhere near the button.

The two formats are built for different jobs, and the difference in size is not a matter of degree.

The measured difference

Encoding identical 1080p30 source material, thirty seconds long, at sensible settings for each format:

Format	30 seconds	Per minute	Per hour
HEVC (H.265)	16 MB	32 MB	1.9 GB
H.264	23 MB	45 MB	2.7 GB
ProRes 422 HQ	320 MB	611 MB	36.7 GB

ProRes is roughly thirteen times the size of H.264 for the same picture, and around nineteen times HEVC. An hour of it is comfortably over 35 GB, and that is at 1080p; at 4K the figures multiply again.

If a drive lost a few hundred gigabytes without explanation, a folder of ProRes is a strong candidate.

Why the difference exists

It is a design decision, not inefficiency.

H.264 and HEVC are inter-frame formats. They store a full frame occasionally and then describe subsequent frames as changes from the previous ones. That is enormously efficient for footage where most of the picture stays put, which is most footage. The cost is that reconstructing any given frame means decoding the frames it depends on.

ProRes is intra-frame. Every frame is compressed independently and stands alone. Nothing refers to anything else. That is why scrubbing through ProRes in an editor is instant and scrubbing through highly compressed H.264 is not: the editor can jump to any frame and decode just that one.

It also means every frame pays full price in storage, including the ones that are nearly identical to their neighbours. That is where the thirteenfold difference comes from.

Which to use, and when

ProRes while you are working. If you are editing, grading or compositing, ProRes earns its size. Responsive scrubbing, no generational loss when you re-render, and enough colour information to push the image around without it falling apart.

H.264 or HEVC for anything finished. If the footage is done and you are keeping it, or sending it, or putting it on a website, there is no reason to store it intra-frame. Nobody scrubs an archive.

The mistake is leaving an export set to ProRes because it sounded like the quality option, and then keeping the output. The quality gain is real and it only matters if you are going to process the file further.

Converting an archive

If you have ProRes files you have finished with:

ffmpeg -i archive.mov -c:v libx265 -crf 20 -tag:v hvc1 \
  -preset medium -c:a aac -b:a 192k archive.mp4

-crf 20 is a high-quality setting; the result is visually very close to the source at a fraction of the size. -tag:v hvc1 keeps it playable in QuickTime and Safari, which HEVC otherwise sometimes is not.

For maximum compatibility, particularly with older Windows machines, use H.264 instead:

ffmpeg -i archive.mov -c:v libx264 -crf 20 -preset medium \
  -pix_fmt yuv420p -c:a aac -b:a 192k archive.mp4

Manatee does this on the Mac without a command line and without uploading anything, working from a duplicate so the ProRes original remains until you decide to delete it. That last part matters here: check the converted file before removing the source, because the conversion is not reversible.

Reducing MP4 file size without losing quality covers where quality actually goes when you compress, and why compressing a video twice makes it look worse explains why you should convert from the ProRes rather than from an already-compressed copy.

The ProRes variants

Not all ProRes is the same size, and picking the right one saves a great deal without changing your workflow:

ProRes 422 Proxy and ProRes 422 LT are for offline editing and reviews. Considerably smaller.
ProRes 422 is the general-purpose middle.
ProRes 422 HQ is the common default for finishing, and the one measured above.
ProRes 4444 adds an alpha channel for compositing and is larger again.

If something is exporting 4444 and you are not compositing, you are storing an alpha channel of nothing. Check the export preset.

A rule that works

Ask what happens to the file next.

If the answer involves another program processing it, keep ProRes. If the answer is that someone watches it, or it sits on a drive in case you want it one day, it should be H.264 or HEVC. The category people get wrong is the second one, where “I might edit it again” leads to storing an entire project intra-frame indefinitely.

For genuine masters, a compromise: keep the original camera files, which are already efficiently compressed, and re-create the ProRes intermediates if you ever need them. The camera originals are the real archive.

Questions

Does converting ProRes to HEVC lose quality? Some, in principle. At -crf 20 it is very hard to see. If you might grade the footage again, keep the ProRes; if you are watching it, convert.

Why is my ProRes file bigger than the camera original? Because the camera recorded in an efficient inter-frame codec and your editor exported an intra-frame one. That is normal, and it is why exporting ProRes from phone footage produces a file many times larger than the source with no visible improvement.

Is ProRes better quality than H.264? At the same file size, yes, substantially. At sensible settings for each, both look excellent, and the differences appear when you process the file further rather than when you watch it.

Should I record ProRes on my iPhone? Only if you are grading the footage and have somewhere to put it. It fills storage remarkably quickly, and for ordinary recording the standard mode is the better choice.