SNDT to GSM Converter
Processing entirely on your device — large files may take a moment.
Convert GSM speech recordings to WAV or MP3. If your files are still in SNDT format, this page is the shortcut: SNDT is the Sound Tool sample format for MS-DOS — an uncompressed raw PCM cousin of SNDR found in retro archives.
iLoveConverter processes everything locally on your computer, which makes it private and fast: no upload wait, no server storage, no limits. Add as many files as you like — batch conversion is built in.
How SNDT compares to GSM
| SNDT | GSM | |
|---|---|---|
| Structure | MS-DOS Sound Tool container | Raw GSM frames (33 bytes/20ms) |
| Compatibility | ffmpeg, archive tools | Asterisk, SoX, ffmpeg |
| Best for | Rescuing legacy audio | Telephony recordings |
How to convert SNDT to GSM
- 1
Select your files
Drag & drop your SNDT files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to GSM". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted GSM file individually, or grab everything at once as a ZIP archive.
About the SNDT format
SNDT is the Sound Tool sample format for MS-DOS — an uncompressed raw PCM cousin of SNDR found in retro archives.
ffmpeg decodes it natively inside your browser — the audio track is re-encoded to your chosen format with nothing ever uploaded.
+ Strengths
- ✓Decoded natively by ffmpeg
- ✓Runs entirely in your browser
- ✓Free, private, no watermarks
! Limitations
- −Legacy niche format
- −Modern tools rarely open it
- −Keep the original for archival round-trips
About the GSM format
GSM 06.10 is the speech codec of the original GSM mobile network — 13 kbit/s RPE-LTP that made digital cellphone calls possible in 1991 and still lives inside VoIP systems, old answering machines and Asterisk PBX recordings.
It is lossy speech, not music: converting GSM to WAV or MP3 preserves intelligibility perfectly while finally letting desktop players open the file without special codecs.
+ Strengths
- ✓Tiny bitrate for speech intelligibility
- ✓Ubiquitous in telephony systems
- ✓Decodes natively via ffmpeg
! Limitations
- −Speech-only quality — music falls apart
- −13 kbit/s artifacts are audible
- −8000 Hz sample rate only
Why convert SNDT to GSM?
Think of it as moving your file to the container that fits the job. Legacy niche format GSM works differently: Tiny bitrate for speech intelligibility If any of that sounds like your task, run the conversion — it takes seconds and nothing leaves your device.
Frequently asked questions
Is this SNDT to GSM converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for SNDT to GSM?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Will converting SNDT to GSM reduce audio quality?
If GSM is lossless, the output contains everything the SNDT file contains — no further loss is added. If GSM is lossy, one recompression pass is unavoidable; the quality slider controls how much. Loss that already happened in the source file can never be undone by converting.
Can I convert a whole folder of SNDT files?
You can select many files at once and they are processed in a single batch. Output files land in one ZIP download when there is more than one result.