FLV to MP3 Converter

AUTO-DELETE/Files are processed on our server and deleted as soon as conversion finishes.

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How to Convert FLV to MP3 Online

FLV to MP3: what changes in the file

This tool takes a FLV file, processes it with FFmpeg on DownloadVideo.vn servers and returns a MP3 file.

The picture track of the FLV is dropped; only the audio is kept and packaged as MP3.

Both FLV and MP3 are lossy, so converting adds another generation of compression: a small further loss that is usually hard to notice after one conversion.

How FLV and MP3 differ

Property	FLV	MP3
Full name	Flash Video	MPEG-1 Audio Layer III
Introduced	Macromedia/Adobe, 2003	Fraunhofer / MPEG, 1993
Compression	lossy	lossy
Common codecs	Sorenson Spark, VP6, H.264, MP3, AAC	—
Strengths	common in old video archives and early streaming downloads	plays everywhere: phones, cars, speakers, browsers; about 1 MB per minute at 128 kbps
Limitations	Adobe Flash Player was retired in 2020 — browsers no longer play FLV; phones and modern TVs do not play it	lossy: removed detail cannot be recovered; less efficient than AAC or Opus at the same bitrate

Measured with a sample file

On September 25, 2026 we ran the tool on our production server with a sample file: a 10-second 1280×720 video (FLV1 + MP3), 9.6 MB.

Result: 9.6 MB → 157 KB, processed in 1.4 s. Output: MP3 audio at 44.1 kHz stereo, 128 kbps.

Real sizes depend on your content (how complex the picture and sound are, and the length); the figures only show the order of change.

Before you convert

The tool always re-encodes the picture and sound, even when the source codec would already fit the target format.
Up to 500 MB per file; a conversion that runs longer than 10 minutes is cancelled.
The file is sent to our server for conversion and deleted as soon as processing ends, including when it fails.

Frequently asked questions

Is the picture from the FLV kept in the MP3?

No. MP3 is an audio format, so only the sound is kept.

Does converting FLV to MP3 reduce quality?

Slightly: it is a second round of lossy compression. One conversion is usually hard to notice, but repeated conversions add up.

How does the file size change from FLV to MP3?

With our sample file: 9.6 MB → 157 KB. Your file may differ depending on its content.