4chan video size limit.

A file budget divided by duration gives you a bitrate. For a 30 second clip targeting 4 MB with 96 kbps of audio:

(4,194,304 bytes x 8) / 30s / 1000 = 1118 kbps total
1118 - 96 kbps audio  = 1022 kbps of video

Basketweaver runs this for you and steps the resolution down when the numbers cannot be met at a watchable quality.

Open the converter with the 4chan target already set, or convert on your phone:

The 4096 KB ceiling is the constraint this converter was built around, which is why its output is capped at exactly 4 MiB. VP8 video with Vorbis audio is the long-standing safe combination. Two things vary and are not asserted here: sound is only played on some boards, and the maximum duration has been reported as both 300 and 120 seconds. Check the posting form on the board you are using, which states that board's current limits.

What is the largest video I can upload to 4chan?

4chan accepts uploads up to 4 MB. That figure was read on 2026-09-01 from a community reference, not official documentation.

How do I get a video under 4 MB?

Convert it to WebM with Basketweaver. Output is capped at 4 MB, which is inside 4chan's 4 MB ceiling, so a converted clip always fits. Conversion runs on your own device or in your own browser.

What bitrate do I need for a 30 second clip?

Budget 1022 kbps of video alongside 96 kbps of audio. That is the target size in bits divided by the duration, minus the audio track. Basketweaver works this out for you and lowers the resolution when the maths cannot be met.

Is this limit still current?

It was checked on 2026-09-01 against a community reference, not official documentation. Platforms change these quietly, so the source is linked on this page for you to confirm.