Compress preset

Compress Video for Slack

500 MB targetFree tier per-fileH.264 MP4

Slack allows up to 1 GB per file on every plan, including free. Despite that generous per-file cap, the real constraint is workspace storage. Slack Free gives you 5 GB total across all files in the workspace; paid plans raise the quota to 10 GB per member, 20 GB per member on Business Plus, and 1 TB per member on Enterprise Grid. Once the quota is hit, the oldest files start becoming inaccessible on free plans or counting against your bill on paid plans. Compressing screencasts and design walkthroughs before upload keeps the quota healthy and search results fast.

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Compressing for Slack in detail

The recommended tier is 500 MB, which fits a full 15 to 20 minute 1080p engineering incident walkthrough without quality collapse. Stand-up updates work well at 100 MB, and quick reaction clips rarely need more than 25 MB. Slack automatically generates a preview thumbnail from the upload and embeds the player inline in the channel, so compression quality genuinely matters. A poorly encoded 800 MB file looks worse in Slack's inline player than a well-encoded 200 MB one.

Everything runs in your browser, which means proprietary material in the screencast, customer data in bug reports, or confidential design reviews never leave your device during compression. Only the finished MP4 goes up to Slack.

Slack storage and upload limits

Setting	Value	Notes
Per-file upload cap	1 GB	Applies on every Slack plan including Free.
Free workspace storage	5 GB total	Shared across all members and files.
Pro workspace storage	10 GB per member	Scales with active member count.
Business Plus storage	20 GB per member	Higher tier for larger orgs.
Enterprise Grid storage	1 TB per member	Effectively unlimited for most teams.
Inline player codec	H.264 / AAC	MP4 containers preview; MKV or AVI download only.

When to use this preset

Engineering incident walkthroughs

Record a 15 minute postmortem screencast, compress to 500 MB, and post in the incident channel where the team can scrub through it inline.

Design feedback loops

Drop a 100 MB Figma walkthrough into a thread so stakeholders can react without pulling up Zoom.

Async standup updates

Daily standup as a 25 MB compressed clip that does not balloon workspace storage over a quarter.

Hiring loop debriefs

Compress panel debrief recordings to 500 MB and post in a private hiring channel for the full loop to review.

Customer support video replies

Send a 100 MB annotated screencast to a customer through a shared channel so they can see exactly which setting to change.

Frequently asked questions

What is the Slack file size limit?

Slack allows up to 1 GB per file on every plan, including free. The practical limit is the workspace storage quota: 5 GB total on Free, 10 GB per member on Pro, 20 GB per member on Business Plus, and 1 TB per member on Enterprise Grid. Large uncompressed video uploads can blow through the quota fast on Free plans.

How do I upload a large video to Slack?

For files under 1 GB, drop them directly into a message. For files larger than 1 GB, upload to a cloud service like Google Drive or Dropbox and paste the link, which Slack will unfurl with a preview. Compressing the file below 500 MB first is usually the right call because the inline player performs better with smaller files.

Does Slack compress videos?

Slack does not re-encode uploaded video. It stores the exact bytes you upload and streams them on demand. A 900 MB H.264 MP4 uploaded to Slack is still 900 MB in the inline player. That is why compressing locally before upload is worth the five minutes it takes: you control the output quality and the storage hit.

Why won't my video upload to Slack?

Usually because the file is over 1 GB, or the workspace storage quota is full on a Free plan. Slack also sometimes rejects unusual container formats. MP4 with H.264 always works; MKV and older MOV files occasionally fail to upload or preview. If the upload silently stalls, check the storage quota in workspace admin first.

What video format is best for Slack?

MP4 with H.264 video and AAC audio. That combination previews in the inline player, shows a correct thumbnail, and streams when scrubbed. WebM, MOV, and MKV may upload but often fail to preview, forcing teammates to download before watching. This tool outputs the correct combination by default.

Can I share videos in Slack DMs?

Yes. DM attachments follow the same 1 GB per-file cap and the same workspace quota. A useful pattern is to compress screencasts heavily for DMs since they are usually one-off clips that you do not need in the channel record; 25 or 50 MB is plenty for a short walkthrough.

How does Slack handle long videos?

The inline player supports seeking, playback speed, and captions if you upload an SRT alongside. Longer videos work fine up to 1 GB, but compressed 500 MB files scrub more smoothly because Slack's CDN can buffer the whole file in memory for most users. Aggressive compression of long talks pays off in playback quality.

100% Private: Your Video Never Leaves Your Device

Compression runs locally in your browser using FFmpeg compiled to WebAssembly. Your video file is read from disk into browser memory, processed there, and the result is saved back to your device. No network request is made during encoding, no data is transmitted, and no server ever sees your footage.