Video Compressor
Compress video files in your browser using FFmpeg.wasm — nothing is uploaded, free and private. Supports MP4, WebM, MOV, and AVI. No account needed — works instantly in your browser.
Video Compression Calculator
Trying to compress a video for Discord, Twitter, or email? Instead of guessing settings and waiting for Handbrake to render, use this tool to calculate the exact Video Bitrate needed to hit your target file size perfectly on the first try.
Required Video Bitrate
How to use this setting in Handbrake:
- Go to the Video tab.
- Select Avg Bitrate (kbps).
- Enter XXXX.
- Check 2-pass encoding for best results.
What Is a Video Compressor?
A video compressor reduces the file size of a video by re-encoding it at a lower bitrate — making it easier to upload to social media, share via email, or store without consuming excessive disk space. This tool compresses video entirely in your browser using FFmpeg compiled to WebAssembly (FFmpeg.wasm), which runs the full FFmpeg video processing engine directly on your device. Your video is never uploaded to any server.
Video compression works by reducing the amount of data stored per second of video. The trade-off is always quality vs. file size — lower bitrate means smaller file but potentially visible quality loss. This tool also includes a bitrate calculator for precise targeting: if you need a video to hit exactly 25MB for Discord or a specific email limit, you can calculate the exact bitrate needed before compressing.
How to Compress a Video
- 1 Select your video file.
Click to upload an MP4, WebM, MOV, or AVI file from your device. The file loads into browser memory only — nothing is uploaded to any server.
- 2 Set compression settings.
Choose a target quality or bitrate. Lower bitrate means smaller file size. For social media uploads, a moderate setting is usually sufficient. Use the bitrate calculator to hit an exact target file size.
- 3 Compress the video.
Click Compress. FFmpeg.wasm processes the video entirely in your browser. This may take a moment depending on file size and your device's CPU — a 5-minute video may take 1–3 minutes to process.
- 4 Download the compressed file.
Click Download to save the compressed MP4 to your device. The output uses H.264 encoding for maximum compatibility.
Who Is This For?
Content creators reducing video file size before uploading to social media, YouTube, or a CMS — compressing recordings without relying on platform-side compression that degrades quality.
Developers preparing demo videos and screen recordings for documentation, landing pages, or README files where smaller file size directly affects load time.
Anyone who needs to compress a video without installing software or uploading footage to a cloud service — especially for proprietary or confidential recordings.
Key Benefits
FFmpeg.wasm runs entirely in your browser. No video data is transmitted to any server at any point.
No subscription, no upload caps, no watermarks. Compress as many videos as you need.
Upload, compress, and download without signing up, providing an email, or installing anything.
Powered by FFmpeg.wasm — the same engine professionals use in command-line workflows, running locally in your browser tab.
The Math Behind Video File Sizes
Video file size is determined by two factors: total runtime and total bitrate (data per second). Resolution and frame rate influence visual quality, but they do not override the mathematical ceiling set by your bitrate.
// The Core Calculation
Total Kilobits = Target Megabytes × 8192
Total Bitrate = Total Kilobits ÷ Duration in Seconds
Video Bitrate = Total Bitrate − Audio Bitrate
For example, to hit exactly 25MB in 2 minutes: (25 × 8192) ÷ 120 = 1,707 kbps total. Subtract ~128 kbps for audio = ~1,579 kbps video bitrate. Use 2-pass encoding in Handbrake or FFmpeg with this target bitrate and your output will hit 25MB accurately.
Common Use Cases
Social media upload preparation
Compress a high-quality screen recording or camera footage to meet Instagram's, TikTok's, or Twitter's file size limits without platform re-compression degrading quality.
Discord video sharing
Use the bitrate calculator to target exactly 25MB (or 50MB for Nitro) before compressing — your video will share successfully without the "file too large" error.
Documentation and landing page videos
Compress product demos, explainer clips, and onboarding videos to under 5MB for embedding in docs or landing pages — fast load times, no reliance on YouTube or Vimeo.
Email and file transfer
Reduce a screen recording from 200MB to under 25MB for email attachment, or prepare clips for services with file size limits without quality-destroying online converters.
Frequently Asked Questions
What is a video compressor? ▼
A video compressor reduces the file size of a video by re-encoding it at a lower bitrate. This tool compresses video entirely in your browser using FFmpeg.wasm — no video is uploaded to any server. The compressed file is downloaded directly to your device.
Can video compression happen in a browser without uploading? ▼
Yes. This tool uses FFmpeg compiled to WebAssembly (FFmpeg.wasm), which runs the full FFmpeg video processing engine directly inside your browser. Your video file never leaves your device — you can disconnect from the internet after the page loads and the tool will still work.
Is this video compressor free? ▼
Yes, completely free. There are no file size limits, no account required, and no subscription. All compression happens locally in your browser using FFmpeg.wasm — no server costs, no paid plans.
What video formats are supported? ▼
MP4, WebM, MOV, and AVI are supported as input formats. The tool outputs MP4 (H.264) for maximum compatibility across platforms, devices, and browsers.
Why is my compressed video still large? ▼
Video file size is primarily determined by bitrate multiplied by duration. A 1-hour video at 2 Mbps is still 900MB regardless of resolution. To get smaller files you can reduce the target bitrate, lower the resolution, or trim the video to only the needed section before compressing.
What is the best video size for social media? ▼
Instagram Reels and TikTok recommend files under 650MB. Twitter has a 512MB limit. Discord's standard limit is 25MB (50MB with Nitro). For most social media uploads, compressing to a 5–10 Mbps bitrate at 1080p will produce a good balance of quality and file size.
The tools and calculators provided on The Simple Toolbox are intended for educational and informational purposes only. They do not constitute financial, legal, tax, or professional advice. While we strive to keep calculations accurate, numbers are based on user inputs and standard assumptions that may not apply to your specific situation. Always consult with a certified professional (such as a CPA, financial advisor, or attorney) before making significant financial or business decisions.
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