Video Size Reducer is a browser tool focused on shrinking a single video to a specified size. It is aimed at users who cannot upload videos due to platform limits, such as Discord's free upload limit of about 10MB, Gmail's 25MB attachment limit, and platforms like WhatsApp, Reels, TikTok, Shorts, and X that re-encode uploaded content.
Main capabilities
- Platform presets and custom targets: You can choose presets such as Discord, Gmail, WhatsApp, Reels, TikTok, Shorts, and X, or enter a custom MB value, and the tool will work backward from that to determine the compression budget.
- Local compression: By default, the entire compression process is completed within the browser tab. After the page reads the file metadata, it uses the WebAssembly version of ffmpeg to transcode locally, and the compressed file is downloaded directly from the same tab. The source file is not uploaded, and there is no server-side copy.
- Metadata pre-check: Before compression begins, it reads the file size, duration, resolution, and container type, making it easy to check feasibility against the target.
- On-demand encoder loading: The WebAssembly version of ffmpeg is loaded only when a task actually starts, keeping the initial page lightweight.
- Single-file processing: Only one video is processed at a time; choose one clip, one target, and get one smaller downloaded file. Batch tasks belong to the cloud path.
- Explanation when the target is not met: If the target cannot be achieved, the tool clearly says so and explains why, rather than quietly returning a file that is still over the limit. Users can choose to relax the target, accept lower quality, or switch to cloud processing.
How to use
- Choose a target: Select a platform preset, or enter a custom MB value, so the tool knows the budget the output must meet.
- Run local compression: Drag in the file, confirm the metadata, and start. The encoder loads, progress is shown in the tab, and slow tasks can be canceled.
- Download and verify: The completed file downloads locally, and the actual size is displayed so you can confirm whether it meets the platform limit.
Local boundaries and the cloud path
- Desktop Chrome is the reference environment, and local compression is suitable for source files of about 300MB or 10 minutes or less. Other desktop browsers perform roughly similarly.
- Mobile is best-effort; background tabs may be reclaimed mid-transcode, so processing shorter clips on mobile is recommended.
- Files that exceed the local window will not start a transcode doomed to fail, but will instead be directed straight to a cloud processing interest registration. The cloud path is aimed at larger, slower, batch, or higher-qualityvolume of tasks.
Compression and quality
- The compression ratio is the target size divided by the source size. Cutting 30% to 50% usually keeps quality close to the original; going beyond 90% noticeably changes the picture.
- The bitrate budget is the target size divided by the duration. For example, limiting a 5-minute video to 10MB gives a total bitrate of about 260 kbps, which forces low resolution and produces obvious artifacts.
- If the target platform allows 25MB, landing at 24MB is better than compressing to 10MB.
- Source files that are already highly compressed are hard to shrink substantially further; static talking-head scenes compress much better than handheld motion or confetti scenes.
- Common formats such as MP4 and WebM are safe choices for local compression, and other containers can also be tried; reading metadata before compression will show what the browser actually recognizes.
Free and account This tool requires no account or payment and can be used as soon as you open the browser.
Limitations and notes
- Only one video can be processed at a time; batch processing is not supported.
- Local encoding in the browser is slower than desktop applications because the encoder is ffmpeg compiled to WebAssembly and runs under the memory limits of a tab.
- Background tabs on mobile may be reclaimed, causing transcoding to be interrupted.
- When the source file exceeds about 300MB or 10 minutes, the local path is not suitable and you need to switch to cloud processing.
- Compression always causes some degree of quality loss, and the extent of the loss depends on the compression ratio, the source file, and the video content.
- The page itself, page resources, and the optional cloud interest form access the network, but the video file does not.
