For a new music station using MP3, 128 kbps is a useful starting point. Compare it with 192 kbps using the music you actually broadcast, then decide whether the difference matters to your audience. A speech-led station can also compare a lower rate such as 64 kbps, especially when keeping listener data use low is a priority.
These are starting points for listening tests. The right choice depends on the programme, encoder, source recordings and connections your listeners use. A higher number uses more data; it does not repair a noisy microphone or make a poor recording sound like the original master.
What bitrate means
Bitrate is the amount of encoded audio data sent each second. 128 kbps means 128,000 bits per second. It is different from the sample rate, usually shown in kHz, and from the number of audio channels.
An encoder compresses the programme into a stream. With a lossy format such as MP3, the encoder trades some audio information for a smaller amount of data. The chosen codec and its settings influence the result; bitrate alone is not a complete description of sound quality. MDN's audio codec guide explains these distinctions.
The suggestions below are for MP3, so you can compare them on a consistent basis. Do not assume a 64 kbps stream in another codec sounds identical to a 64 kbps MP3 stream. Codec profiles, encoders and playback support differ.
Compare practical MP3 settings
| Bitrate | Where to begin your comparison | Audio data per listener per hour |
|---|---|---|
| 64 kbps | Speech-led programmes where low data use matters; listen closely to music and jingles | 28.8 MB |
| 128 kbps | A starting point for a music station or a mix of music and speech | 57.6 MB |
| 192 kbps | Compare with 128 kbps when you want to allow more data for music detail | 86.4 MB |
| 256 kbps | Another step to compare if your plan and audience connections suit it | 115.2 MB |
| 320 kbps | A high-rate MP3 option to assess against lower rates, rather than an automatic requirement | 144 MB |
The data figures are calculations for a constant audio bitrate, using decimal megabytes. They exclude network overhead, web pages, adverts and reconnections. They are estimates for the audio stream, rather than a prediction of a phone's total data use.
The Mixxx broadcasting manual also treats bitrate as a balance between audio quality and the connection capacity used by both the broadcaster and listeners.
Speech and music need different comparisons
For a talk station, start with clear microphone technique, sensible input levels and a quiet room. Compare speech at 64 and 128 kbps, including louder words, quiet passages and any music beds. If the programme is mostly mono speech, you can also evaluate mono encoding where your encoder supports it. Check any stereo music before deciding to use mono for the whole station.
For music, compare passages that expose changes clearly: vocals, cymbals, sustained notes and busy mixes. Use the same source recording at each setting. Listen through headphones and through the devices your audience commonly uses, at similar playback levels.
A rate that works well for a spoken interview may be less suitable for the station's music show. Choose for the complete programme, including jingles and transitions, rather than one quiet voice sample.
Listen to the VosCast bitrate examples
Our plan and bitrate guide includes embedded players for the same music sample at several MP3 rates. Compare 64 kbps, 128 kbps, 192 kbps and 320 kbps.
Use those examples to hear the trade-off, then repeat the comparison with your own programme. One sample cannot represent every genre, encoder or listening environment.
How much mobile data does radio use?
For a constant-rate audio stream, the calculation is:
Bitrate in kbps × 0.45 = approximate MB per hour
For example, 128 × 0.45 gives 57.6 MB per hour. Four hours at that rate is about 230 MB of audio. At 320 kbps, four hours is about 576 MB, before overhead or other activity.
At the same bitrate, mono and stereo have the same total encoded data rate. Mono can change how the encoder uses that rate, but choosing mono does not automatically halve data consumption unless you also lower the bitrate.
Consider listeners who use mobile data or unreliable connections. The highest available rate may be unnecessary for the programme and less convenient for those listeners. Check actual playback as well as how the audio sounds in the studio.
Choose a plan and encoder setting together
Your VosCast plan sets a Maximum Bitrate. It is a ceiling: you can broadcast at a lower rate. For example, a plan allowing 192 kbps can carry a 128 kbps broadcast. Setting the encoder above the account's limit is not a way to upgrade it.
Choose the encoder's MP3 bitrate in its audio or encoding settings, using the setup guide for your software. Keep a copy of the working profile and check the public stream after making a change. The plans page lists the current allowances, and our internet radio costs guide explains the other costs to plan for.
A higher output rate cannot restore information already lost from a low-quality file. Start from good recordings and avoid unnecessary lossy re-encoding. Hosted Auto DJ uses uploaded MP3 files; the live encoder settings on your computer do not configure a hosted playlist.
Leave room in the broadcasting connection
A live encoder sends one programme stream to VosCast. Listeners connect to the hosted server, so 100 simultaneous listeners do not require 100 copies to leave your studio computer.
The source connection still needs to sustain the chosen bitrate throughout the show, with room for network overhead and other activity. A short speed test is less useful than checking the actual programme route over a realistic session. If the connection is unstable, investigate it before assuming a higher hosting plan will solve the interruption.
Our buffering and dropout guide helps distinguish source upload problems, missing audio and listener-side playback issues.
Start with a rate your programme and connections can use reliably. Keep it within the account limit, listen to the public stream on another device, and move up only when the difference is useful to your station.