WebM → Instagram Reels
Compress WebM for Instagram Reels
Instagram's uploader rejects WebM outright — neither the mobile app nor the web interface accept .webm files, regardless of size or duration. This is a hard platform-level block, not a compression issue. WebM is what Loom, browser screen recorders, and Chrome-based tools export by default; if you've ever tried to post a Loom clip to Reels, this is why it fails. This page transcodes WebM (VP8/VP9 video, Opus/Vorbis audio) to MP4 H.264 with AAC audio — the format Instagram actually accepts — and crops/letterboxes to 9:16 vertical at 1080×1920 for Reels.
Where do you want to share your video?
How to compress WebM for Instagram Reels
- 1Drag your .webm file onto the upload zone above (or browse to it).
- 2Instagram Reels is already selected. We'll target 500 MB to stay safely under the 4 GB cap.
- 3Optionally trim to a highlight clip in the review screen.
- 4Download the compressed MP4 and share it on Instagram Reels. Compression runs entirely in your browser, the source file never left your device.
What to know about WebM → Instagram Reels
- Instagram's upload dialog gives a generic error for WebM — the file isn't too big, it's unsupported.
- Loom's default 'Download video' gives WebM — this page is specifically for that workflow.
- Horizontal WebM screen recordings get letterboxed to 9:16; add a background graphic in a separate editor for better aesthetics.
- VP9 transcodes to H.264 without visible quality change at Reels bitrates.
The compression math
A 60-second 1080p VP9 WebM screen recording = ~40 MB. Re-encode to H.264 1080×1920 (cropped) at CRF 23 = ~30 MB, well under Instagram's 4 GB cap, ready to upload directly.
About WebM files
WebM is Google's open, royalty-free video format that uses VP8 or VP9 video codecs. It's widely used by browser-based screen recorders (like Loom exports), Chrome extensions, and web applications. While WebM plays natively in Chrome and Firefox, it has poor support on iOS devices and is rejected by most social media platforms. CompressYourVideo.com converts WebM to compressed MP4 (H.264), making it compatible with every device and platform. This is especially common for screen recordings from browser tools, which default to WebM output. The conversion preserves video quality while often reducing file size, since H.264 is more efficient than VP8 at equivalent quality levels.
About Instagram Reels
Compress and optimize videos for Instagram Reels. Instagram Reels supports videos up to 4GB and 15 minutes long, with 9:16 vertical aspect ratio and MP4 H.264 format required. Shorter clips perform best in the algorithm.
Related compression tools
Or compress WebM for a different platform