Which bitrate and format should you choose for your radio stream?
The bitrate is the amount of data your stream sends per second. The higher the bitrate, the better the sound, but also the more data it uses: for you as a station and for your listeners on their mobile plans. Here is how to find the right balance.
MP3 or AAC?
MP3 is the best-known format and really works everywhere: in every browser, on smart speakers, in cars and in old internet radios. AAC (often as AAC+ or HE-AAC) is newer and more efficient: at the same bitrate it sounds better than MP3. So with AAC you can use a lower bitrate and still sound good.
Modern browsers and phones play AAC without problems. If you also want to serve older devices, MP3 is the safest choice. Many stations therefore offer both, via two mount points.
Which bitrate?
| Format and bitrate | Quality | Suitable for |
|---|---|---|
| MP3 96 kbps | Fair | Speech, low costs |
| MP3 128 kbps | Good | Most music stations |
| MP3 192 kbps | Very good | Stations that put quality first |
| AAC 64 kbps | Good | Mobile listening, efficient |
| AAC 96 kbps | Very good | A good standard for music |
For most music stations, MP3 128 kbps or AAC 96 kbps is a fine choice. You hardly hear higher bitrates on a phone or laptop speaker, but you do pay for them in data traffic.
How much data does it use?
A 128 kbps stream sends 128 kilobits per second. That is 16 kilobytes per second, or about 58 MB per hour per listener. A few examples:
- 10 listeners listening for 3 hours: about 1.7 GB.
- An average of 25 listeners, around the clock for a month: about 1 TB per month.
- With AAC at 64 kbps you halve these numbers.
Check with your streaming provider how much traffic and how many simultaneous listeners are included in your plan.
Mono or stereo, and which sample rate?
Broadcast music in stereo. At low bitrates (below 64 kbps) mono can sound better, because all data goes to one channel. A sample rate of 44.1 kHz is the standard and matches almost all music files.
Use the same settings everywhere
Make sure your AutoDJ and your DJs broadcast with the same bitrate and format. If the stream changes format when a DJ goes live, some players drop out and listeners have to press play again. So set the right settings in your DJs' software; read how in going live with BUTT, Mixxx or SAM Broadcaster.
Quality starts at the source
A high bitrate does not make a bad file better. Use good-quality music files, make sure the volume of tracks is equal (normalising) and put a light compressor or limiter on your broadcast. Then your station sounds equally loud and pleasant everywhere, also in the car or on a phone.
Frequently asked questions
What is a good bitrate for internet radio?
For MP3, 128 kbps is a common choice: good quality and little data. With AAC you get similar quality at 64 to 96 kbps.
How much data does a listener use?
At 128 kbps about 58 MB per hour per listener. At 64 kbps it is half that.