Two hours of music a day can use about 1 GB of mobile data in a week at 160kbps. Turn that up to 320kbps and the audio alone comes to roughly 2 GB. That's a useful starting point for a trip, especially when the same allowance has to cover maps, messages and everything else on your phone.
How long will you listen? An hour-long commute still takes an hour's worth of audio whether the playlist contains short singles or extended live tracks. Once you have a rough number of hours, the remaining piece is the bitrate your app uses on mobile data.
What can you do with a 1 GB allowance?
Take a seven-day trip with two hours of listening each day. You have 14 hours to cover. At 160kbps, each hour uses a calculated 72 MB of audio, giving a total of 1,008 MB, or 1.008 GB. At 320kbps, it's 144 MB an hour and 2,016 MB, or 2.016 GB, for the week.
The difference is 1.008 GB before any other traffic. So a 1 GB allowance already falls short of the first example. Keeping the same 14 hours but moving to 96kbps gives 604.8 MB of audio. Another option is to stay at 160kbps and stream ten hours, with the remaining four downloaded on Wi-Fi before departure. The streamed part then comes to 720 MB.
Those are planning choices, not results from a phone test. Artwork, videos, network overhead and changes in stream quality can all move the actual total. Don't allocate the whole data allowance to audio and expect nothing else to use it.
How to calculate a different trip
Audio MB per hour = bitrate in kbps × 0.45
For example, 160 × 0.45 gives 72 MB. Multiply that hourly figure by your listening time. The calculation uses decimal units: eight bits make a byte, and 1 GB is 1,000 MB. The factor converts a rate per second into bytes over an hour.
You can use the same calculation for a shorter commute. Ten hours at 160kbps comes to 720 MB of audio. For other common rates, an hour works out as 43.2 MB at 96kbps, 57.6 MB at 128kbps and 115.2 MB at 256kbps. Our bitrate, sample rate and bit depth guide explains how bitrate differs from the other figures attached to an audio file.
Spotify High and YouTube Music High use different rates
Spotify's documented High setting is approximately 160kbit/s in the app. YouTube Music's High setting has an upper bound of 256kbps. With those rates in the calculation, an hour comes to 72 MB versus 115.2 MB. They're different starting points despite sharing a name.
Spotify's Normal setting is approximately 96kbit/s; Premium's Very High is approximately 320kbit/s. The web player has different rates, and Automatic adjusts to the connection. Lossless is also available on Spotify. Leave it outside this calculation: the fixed-rate figures above aren't a lossless data estimate.
YouTube Music gives Normal an upper bound of 128kbps. Its separate Always High option is 256kbps. The service's wording matters here: “upper bound” leaves room for a lower rate, whereas the arithmetic assumes a constant one.
Set up the music before you leave
Open the cellular-quality setting, rather than only checking Wi-Fi quality. Spotify documents separate choices for the two connections. YouTube Music also offers Wi-Fi-only streaming. A good Wi-Fi choice doesn't have to be your travelling choice, and download quality is another setting again.
Check that the music is downloaded. A title saved to your library may still need to stream. Confirm your travel selection is available offline while you're at home on Wi-Fi. Our offline streaming versus personal files guide explains why subscription downloads and files you own are different things.
Once you've travelled, compare the estimate with the app's mobile-data use recorded by your phone. It gives you something concrete to adjust for the next trip. Include music videos separately; this budget is for audio listening.