Tinker Tools

Video Compressor Instantly

Browser-based video compression using WebM encoding. All processing is done locally in your browser— your videos never leave your device.

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Preview

Drop your video here or click to browse

Supports MP4, WebM, MOV, and other browser-playable formats

How it works

1. Upload Video

Drag and drop or click to upload any video file. Your file stays in your browser and is never sent to any external server.

100% Private

2. Adjust Settings

Choose your target resolution, quality preset, and frame rate. Lower settings produce smaller files with more compression.

Fine Control

3. Download Result

Compare original and compressed file sizes side by side. Download your optimized WebM video with a single click.

Size Comparison

What is Video Compression?

Video compression reduces the file size of a video while trying to maintain visual and audio quality. An uncompressed 1080p video at 30 frames per second generates roughly 1.5 gigabits of data per second — that is about 11 GB per minute. Nobody stores or streams video at that rate. Compression algorithms analyze each frame, find redundancy between consecutive frames, and encode the differences rather than the full image. A 10-minute 1080p clip that would be 110 GB uncompressed can be compressed to 50-150 MB depending on the codec and quality settings. That is a reduction of 99.9%, and the result still looks sharp on a laptop or phone screen.

The magic happens through two types of redundancy removal. Spatial compression looks within a single frame and removes redundant pixel data — large areas of similar color, repeating textures, smooth gradients. This is similar to how JPEG compresses a still image. Temporal compression looks across frames and finds regions that have not changed — a static background behind a moving subject, for example. Instead of encoding that background 30 times per second, the codec stores it once and references it in subsequent frames. Modern codecs like H.264, H.265/HEVC, VP9, and AV1 use increasingly sophisticated algorithms to exploit both types of redundancy, achieving better quality at lower bitrates with each generation.

This tool compresses your videos directly in your browser using FFmpeg compiled to WebAssembly. There is no upload to a remote server — your video stays on your device throughout the entire process. You pick a codec, set your target quality or file size, and the tool encodes the video locally. The result is a smaller file ready for sharing, uploading to social media, embedding on a website, or archiving on a drive with limited storage.

Key Features and Benefits

  • Modern codec support — Choose from H.264, H.265/HEVC, VP9, and AV1. H.264 is the universal standard — every browser, phone, and smart TV decodes it. H.265 delivers the same quality as H.264 at roughly 40-50% lower bitrate but has limited browser support due to licensing. VP9 is Google's royalty-free alternative with similar efficiency to H.265 and excellent browser support in WebM containers. AV1 is the newest option, achieving 30% better compression than H.265, though encoding is significantly slower. The tool lets you pick the codec that matches your compatibility and quality needs.
  • CRF quality control — Constant Rate Factor is the standard way to control quality in modern encoders. Instead of setting a fixed bitrate — which wastes bits on simple scenes and starves complex ones — CRF lets the encoder allocate bits where they are needed. For H.264, CRF values range from 0 (lossless) to 51 (worst quality). A CRF of 18 is visually transparent to most viewers. A CRF of 23 — the default — produces good quality at a reasonable file size. Each increment of 6 roughly halves the bitrate. The tool exposes this slider so you have precise control over the size-quality tradeoff.
  • Resolution scaling — Downscaling a 4K video to 1080p before compression cuts the pixel count by 75%, which translates directly into a smaller file. The tool offers preset resolutions — 2160p, 1440p, 1080p, 720p, 480p — and a custom option for non-standard sizes. It uses the Lanczos scaling algorithm for sharp downscales. If your video is destined for a phone screen or a social media feed where 4K resolution adds no visible benefit, dropping to 1080p or 720p dramatically reduces file size with no perceptible quality loss at the intended viewing distance.
  • Audio compression — Video files carry an audio track that contributes to the total size. The tool re-encodes audio using AAC at 128-256 kbps for MP4 containers or Opus at 64-192 kbps for WebM. Opus is remarkably efficient — 96 kbps Opus is roughly equivalent to 128 kbps AAC in listening tests. For videos where the audio is secondary — screen recordings, surveillance footage, silent clips with background music — you can drop the audio bitrate to 64 kbps or remove it entirely to save space.
  • Container format selection — The container is the wrapper that holds the video and audio streams together with metadata. MP4 is the most widely compatible — it works in every browser, every phone, and every media player. WebM is the open-source alternative favored by web platforms and supported in all modern browsers. MKV is the most flexible, supporting virtually any codec and multiple audio or subtitle tracks, but browser support is limited. The tool lets you choose the container that fits your distribution channel.
  • Browser-based processing with FFmpeg.wasm — The compression engine is FFmpeg compiled to WebAssembly, running entirely in your browser tab. This gives you access to the same encoding algorithms that professionals use on the command line, without installing anything and without sending your video to a server. Processing speed depends on your CPU — a 5-minute 1080p clip encoded with H.264 CRF 23 takes roughly 2-8 minutes on a modern desktop. The tool shows a progress bar with estimated time remaining so you know what to expect.

How to Compress Video Online

  1. 1

    Upload your video

    Click the upload area or drag your file onto the page. The tool accepts MP4, WebM, MKV, AVI, and MOV files up to 2 GB. It reads the file locally and displays key information — duration, resolution, current codec, bitrate, and file size. This analysis helps you decide how aggressively to compress. A 500 Mbps screen recording has far more compression headroom than a 5 Mbps web video that has already been optimized.

  2. 2

    Select a codec and container

    Choose your output codec and container format. For maximum compatibility, pick H.264 in an MP4 container. For the best compression ratio with modern browser support, try VP9 in WebM. For cutting-edge efficiency and you can tolerate slower encoding, select AV1. The tool shows a compatibility matrix so you know which devices and browsers will play the output without issues.

  3. 3

    Set quality and resolution

    Adjust the CRF slider to set your quality target. Start at the default value — 23 for H.264, 31 for VP9, 30 for AV1 — and go lower for better quality or higher for smaller files. If you want to downscale, pick a target resolution from the dropdown. The tool estimates the output file size based on your settings, though the actual size depends on the video content — fast action compresses less efficiently than talking heads.

  4. 4

    Configure audio settings

    Choose the audio codec — AAC for MP4 or Opus for WebM — and set the bitrate. For spoken content like podcasts or tutorials, 96-128 kbps is plenty. For music or cinematic audio, use 192-256 kbps. If the video has no meaningful audio, disable the audio track entirely to eliminate that portion of the file size. You can also adjust the sample rate — 44.1 kHz is standard for music, 48 kHz for video production.

  5. 5

    Compress and download

    Click the compress button. The FFmpeg.wasm engine encodes the video frame by frame, showing a progress bar and time estimate. Once finished, you see the output file size, the compression ratio, and a playback preview. If the quality is not what you wanted, adjust the CRF and run it again — the tool keeps your settings so iteration is fast. When you are satisfied, click download to save the compressed file.

Expert Tips for Video Compression

Match the codec to your audience. H.264 plays everywhere — iOS, Android, Windows, macOS, Linux, smart TVs, game consoles, and every web browser released in the last decade. If you are distributing a video and you do not know what your viewers will use to play it, H.264 in MP4 is the safe choice. VP9 offers better compression and works in Chrome, Firefox, and Edge, but Safari only added support in macOS Big Sur and iOS 14. AV1 has the best compression but requires recent hardware or software decoders. Encoding for the wrong audience means some viewers will see an error instead of your video.

Use two-pass encoding for size-critical outputs. The default single-pass CRF mode optimizes for consistent visual quality — the file size is whatever it needs to be. If you have a strict size limit — say, 25 MB for an email attachment or 8 MB for a Discord upload — two-pass encoding is more effective. The first pass analyzes the video and builds a complexity map. The second pass distributes bits based on that map to hit your target file size while maintaining the best possible quality throughout. The tool supports this mode for H.264 and VP9.

Do not re-encode already compressed video unless you have to. Every generation of lossy compression degrades quality. If someone sends you an H.264 MP4 and you re-encode it to H.264 at the same quality level, the output will be slightly worse than the input — you are compressing artifacts from the first encode. If you just need to change the container — MP4 to MKV, for example — use a converter tool that remuxes without re-encoding. Save re-encoding for situations where you genuinely need to reduce the file size or switch to a different codec.

Pay attention to the encoding speed preset. H.264 and H.265 offer presets from ultrafast to veryslow. Slower presets produce smaller files at the same quality because the encoder spends more time finding optimal compression decisions. The difference between medium and slow is typically 5-10% smaller files for about twice the encoding time. Going from slow to veryslow saves another 2-3% but triples the time. For most users, the medium or slow preset hits the right balance between encoding speed and compression efficiency. The tool defaults to medium but lets you choose a slower preset when file size matters more than waiting.

Related Tools

Video Format Converter

Change container formats or codecs without necessarily recompressing the video

GIF Maker

Convert short video clips into animated GIFs for embedding where video is not supported

Image Compressor

Compress thumbnail images extracted from your video for web use

Video compression is one part of a broader media optimization workflow. You might convert a MOV file from your camera to a web-friendly MP4, compress it to fit a platform's upload limits, and extract a short clip as a GIF for a social media post. Or you might compress a screen recording, then generate a thumbnail image and compress that separately for a webpage. Each tool in the chain runs locally in your browser — no uploads, no accounts, no waiting for server-side processing. Your videos and the data they contain stay on your machine from the moment you open the file to the moment you share the final output.

Frequently Asked Questions

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