While switching to Apple Music’s streaming service could dramatically expand your musical horizons, it could also cost you more than Apple’s $9.95-per-month subscription fee. That’s because the volume of bits required by Apple Music’s streaming could vault you past the limit of your phone’s data plan.

To gauge your financial risk, you need to know two things: how much data Apple Music requires, and how much data your existing cell-phone plan allows. Both of those calculations can be complicated.

Bandwidth on the run

The problem with calculating the Apple Music’s data demands is that Apple itself doesn’t say how much bandwidth its streaming service requires.

On Tuesday Mashable reported (without disclosing a source) that Apple Music streams will run at 256 kilobits per second.

In our own quick-and-dirty testing, my colleague Dan Tynan used the bandwidth gauge built into iOS (Settings > Cellular) to see how much data an hour of Apple Music streaming to his iPhone 6 via LTE would burn up. The answer: exactly 50 megabytes, for a bit rate of about 128 kbps.

I found other solid clues on Reddit. There, one user, xavier86, identified support for 64 kbps, 128 kbps and 256 kbps streams in an Apple Music streaming file’s metadata. Another, HeroPiggy95, located distinct 64, 128 and 256 kbps streams that played in non-Apple apps, including the Chrome browser on an Android tablet I tried.

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What sort of connection speed will flip your Apple Music Stream from 50 MB an hour to the 100 MB an hour of the maximum-quality stream? Apple PR has not responded to our inquiries, but a tweet from Apple’s Eddy Cue hints that you’ll get 256 kbps only when streaming via WiFi. We may have to wait for further crowdsourced research to get a conclusive answer.

Comparing streams

Even if Apple Music were streaming at 128 kbps, however, that would be double the 64-kbps bit rate of Pandora’s mobile app. In my own testing, that service’s Android app ate up only 21.39 MB over an hour. At that rate, I could listen for an hour a day and still rack up only 663 MB of data-usage in a month.

Spotify’s usage sits between Pandora’s and Apple’s: Its “normal” rate is 96 kbps, while “high quality” uses 160 kbps. And that service offers a still-higher 320 kbps bit rate for paying subscribers.

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