Any file up to 500 MB. Drop several files and they come back as one ZIP. Many image, audio and video conversions run in your browser; anything else is uploaded and removed within the hour.
Extract high-quality audio tracks from your video files with our MKV to FLAC converter. This tool is ideal for users who want to isolate soundtracks from movies or concerts for pure audio playback.
MKV is a versatile multimedia container designed to hold video, multiple audio streams, and subtitles, while FLAC is a dedicated audio format providing lossless compression. When converting MKV to FLAC, the process involves stripping the video stream and re-encoding the audio track into the FLAC container. Because you are shifting from a video-centric environment to an audio-only format, the file structure changes significantly, often resulting in a larger file size due to the uncompressed nature of the FLAC stream.
Since the source audio in an MKV file is often compressed (like AC3 or AAC), converting to FLAC will not improve the original sound quality; it merely preserves the existing fidelity without further degradation.
We built this project so anyone can convert files without paywalls, accounts, or hidden limits. Here is what that promise means in practice.
Every converter on ConvertX is free to use: no trials, no premium tiers, and no credit packs. We will never put core conversion features behind a subscription. Whether you convert one photo or a hundred files a week, the price stays zero.
Many image, audio, and video conversions run entirely in your browser. Your files never leave your device for those jobs. When server processing is required for documents or specialized formats, uploads are handled securely and removed automatically — typically within one hour.
A quick guide to strengths and trade-offs of popular formats — so you pick the right one before converting.
Clips, streams, screen recordings, and movies.
Common extensions: MP4, WebM, MOV, MKV, AVI, MPEG
Raster and vector graphics for web, print, and photography.
Common extensions: PNG, JPG, WebP, AVIF, GIF, SVG, HEIC, TIFF
Office files, PDFs, ebooks, and plain text.
Common extensions: PDF, DOCX, XLSX, PPTX, ODT, EPUB, TXT
Music, podcasts, voice recordings, and sound effects.
Common extensions: MP3, WAV, FLAC, OGG, AAC, M4A, OPUS
