Convert AMR to 3GP — Free Online Converter

AMR (Adaptive Multi-Rate) is the default voice codec used by GSM mobile networks worldwide, encoding speech at bit rates between 4.75 and 12.2 kbps. Converting AMR recordings to 3GP wraps the audio inside a 3GPP multimedia container that older feature phones and Android devices handle natively. Because 3GP is essentially a lightweight MPEG-4 profile designed for cellular networks, the resulting file keeps the tiny footprint AMR is known for while gaining broader playback support on mobile handsets.

Standalone .amr files are difficult to share — most messaging apps and email clients refuse to attach or preview them. Packaging the same AMR audio stream inside a 3GP container makes the file recognizable to media players on virtually every phone sold in the last two decades. 3GP also allows you to add metadata such as a title or timestamp, which raw AMR files cannot carry. If you plan to embed the recording in an MMS message, 3GP is the expected container on many carriers.

The conversion remuxes the AMR-NB stream into a 3GP container (MPEG-4 Part 12 profile) without re-encoding, so there is zero quality loss and the process is nearly instantaneous. FFmpeg copies the AMR audio track directly using stream mapping. The 3GP container adds a few hundred bytes of header overhead but does not alter the underlying codec data.