Answer
Can a browser play 6K video?
Only if the viewer's decoder can.
Sometimes. H.264 and HEVC both allow frames up to 8,192 x 4,320, so a 6K file is within what the codecs allow. Whether it plays depends on the decoder in the viewer's machine, and Windows' built-in decoders document a 4,096 x 2,304 maximum. Test on your client's own computer, and when you do not know who will watch, send a 4K cut alongside the 6K master.
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By uncompressed.io · Updated September 2026
The short answer
The codec is not the limit,
the decoder is.
A browser can play a 6K file when the machine it runs on can decode a frame that size. The codecs are not what stops it. The decoder is, and decoders differ from one computer to the next.
8,192 x 4,320
H.264 and HEVC frame limit
What the codecs allow, per MDN. Not a browser figure.
4,096 x 2,304
Windows built-in decoders
Media Foundation H.264 and HEVC maximum, per Microsoft.
1,920 x 1,088
Guaranteed DXVA size
Above it, hardware if supported, otherwise software.
120 Mbps
6K to 8K export
Upper end of our recommended review export.
Two sets of numbers get confused. The first is what the codec allows. MDN’s video codec guide gives H.264 (AVC) frame sizes up to 8,192 x 4,320 pixels and HEVC from 128 x 96 up to 8,192 x 4,320, varying by profile and level. AV1 goes much further, up to 65,535 x 65,535. A 6K frame sits comfortably inside all three.
The second is what a particular decoder handles. Microsoft documents its Media Foundation H.264 and HEVC decoders, the ones built into Windows, with a maximum resolution of 4,096 x 2,304. Acceleration through DXVA is guaranteed only up to 1,920 x 1,088; above that, Microsoft says decoding uses DXVA if the hardware supports it and software otherwise. Whatever camera produced it, a 6K frame is well over 4,096 pixels wide, so it is above that documented maximum.
What Microsoft’s pages do not say is which browsers use those decoders. So the honest reading is narrow: on Windows’ built-in decoder, 6K is out of range; in a browser, it depends on the decoder that browser uses on that machine and on the hardware underneath. Nobody publishes a table of the largest frame each browser decodes, which is why the answer to this question is a test, not a spec sheet.
Where 6K lands
Inside the codec,
but not under every decoder.
Codec limits from MDN's video codec guide; decoder limits from Microsoft's Media Foundation H.264 and HEVC decoder pages. Neither source says which browsers use these decoders.
The same Microsoft pages add two details worth knowing before you export. The HEVC decoder lists Main, Main Still Picture and Main10 profiles with 4:2:0 chroma only, and the H.264 decoder lists Baseline, Main and High profiles up to level 5.1, 4:2:0 or monochrome. On Windows 7 the H.264 decoder’s maximum drops to 1,920 x 1,088. If your 6K master is 4:2:2, the 4:2:2 playback guide covers that second hurdle.
Apple makes a similar point from the other end: its HEVC support article says resolutions of 1080p or lower, at 60 fps or lower, are more broadly compatible with older devices. The bigger the frame, the smaller the set of machines that play it.
What browsers document
Browsers publish whether HEVC plays,
not how big a frame they decode.
Most 6K review exports are HEVC. Here is what MDN records for each browser. Notice how often the answer depends on hardware support in the device: that is the viewer’s machine deciding, not the browser.
MDN documents whether HEVC plays, not the largest frame each browser decodes. No resolution limit per browser is published there.
On uncompressed.io
Nothing caps the resolution,
and nothing makes it smaller.
There is no resolution rule in the upload path or the player. A 6K export is stored and served as uploaded: no re-encode, no rendition ladder, no downscale. Browser playback uses your uploaded export without another platform re-encode. Codec, device and connection requirements still apply. That cuts both ways. The client sees your 6K file, not a copy of it, and if their machine cannot decode 6K, nothing steps in with a smaller version.
Our recommended review export for 6K to 8K is HEVC Main10, constant frame rate, 2-pass VBR, at up to about 120 Mbps. That is about 900 MB a minute, so the connection matters too; a slow link buffers. The 200 Mbps streaming guide works through that arithmetic.
One check happens at upload. The uploader tries to decode a few seconds of the file in your own browser. If that fails you see “Playback could not be verified in this browser.” and can still choose “Upload original anyway”, so a 6K file is accepted whatever your own machine can play. That check tells you about your computer, not your client’s.
Test before you promise
Four steps,
on the client's machine.
Export the 6K review file
HEVC Main10, 4:2:0, constant frame rate, up to about 120 Mbps. If the master is 4:2:2, make the review file 4:2:0: Windows' built-in HEVC decoder lists 4:2:0 only.
Upload and play it yourself
Watch the upload check. If your own browser cannot verify playback, expect some clients to have the same problem.
Ask the client to press play
On the computer they will review on, not a phone. The watch page prints the stored width and height under the player, so both of you can confirm it is the 6K file.
Keep a 4K cut ready
If it fails or does not play smoothly, upload a 3,840 x 2,160 export as a second film and send that link. Turn on the original download on the 6K film.
For an audience you cannot test
Questions
Frequently asked
Does uncompressed.io make a smaller version for viewers who cannot play 6K?
No. There is no rendition ladder: the player streams the one file you uploaded, at its own resolution and bitrate. If some viewers need a smaller picture, upload a 4K cut as its own film and send that link. A host that builds renditions does this for you automatically, at the cost of re-encoding your file, and if that automatic fallback matters more than the untouched master, that kind of host is the better fit.
Is H.264 safer than HEVC for a 6K file?
Not on the decoder Microsoft documents. Windows' built-in H.264 decoder lists the same 4,096 x 2,304 maximum as its HEVC decoder, and supports Baseline, Main and High profiles up to level 5.1. Switching codec does not get a 6K frame under that limit. HEVC also makes the file smaller at similar quality in theory, per MDN.
The file played when I uploaded it. Will it play for my client?
Not necessarily. The upload check decodes a few seconds of the file in your browser, on your machine. Your client's computer has its own decoder. The only test that answers the question is the client pressing play on the machine they will review on.
What about 8K?
The same logic applies with a bigger frame. MDN's H.264 and HEVC limit is 8,192 x 4,320, and an 8K frame is far above the Windows built-in decoder figure, so the test and the 4K fallback matter even more. The 8K hosting guide covers it in detail.
Host the 6K master and the 4K cut side by side
No resolution cap, no re-encode, and a per-film switch to hand over the original file. The free Starter plan holds 5 GB and one film at a time, enough for a short 6K test clip; hosting both cuts takes a paid plan.
Sources
- 1.Microsoft Learn, H.265 / HEVC Video Decoder (Media Foundation): Main, Main Still Picture and Main10 profiles, 4:2:0 chroma, maximum resolution 4096 x 2304, guaranteed DXVA acceleration up to 1920 x 1088 (last updated January 2021) (fetched 18 September 2026)
- 2.Microsoft Learn, H.264 Video Decoder (Media Foundation): Baseline, Main and High profiles up to level 5.1, maximum resolution 4096 x 2304, 1920 x 1088 on Windows 7 (updated June 2024) (fetched 18 September 2026)
- 3.MDN Web Docs, Web video codec guide: supported frame sizes for AVC and HEVC up to 8,192 x 4,320, AV1 up to 65,535 x 65,535, and HEVC support notes for Chrome, Edge, Firefox and Safari (fetched 18 September 2026)
- 4.Apple Support, Using HEIF or HEVC media on Apple devices: 1080p or lower and 60 fps or lower are more broadly compatible with older devices (fetched 18 September 2026)