platform limit
slack video size limit.
Slack accepts video uploads up to 1 GB. Convert your clip to WebM with Basketweaver and it lands under 4 MB, comfortably inside that limit.
The maths
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.
Three ways to do it
Open the converter with the Slack target already set, or convert on your phone:
Slack specifics
The ceiling is high enough that size is rarely what stops a Slack upload. Workspaces on smaller plans reach their shared storage quota long before any single file reaches 1 GB, so a compact clip mostly buys the workspace room rather than clearing a per-file limit.
Questions
- What is the largest video I can upload to Slack?
- Slack accepts uploads up to 1 GB. That figure was read on 2026-09-01 from Slack's own documentation.
- How do I get a video under 1 GB?
- Convert it to WebM with Basketweaver. Output is capped at 4 MB, which is inside Slack's 1 GB 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 Slack's own documentation. Platforms change these quietly, so the source is linked on this page for you to confirm.