BPM doesn't seem right

Playing “Red Haired Boy”, it has 4 sets of 8 measures in 4/4, so 128 beats total. I set it at 128 BPM and it took 30 seconds to play through the whole song. So the true BPM is 256. Is there a reason the BPM is reported as half (like is it some kind of “split time”)? And I guess more importantly, when people say they are playing a bluegrass song at x BPM, are they really meaning double that amount? So when someone says they play Gold Rush at 200 BPM, are they actually playing it at 400?

Glad you asked. This dichotomy is the result of two common and equally-valid ways of counting beats in bluegrass music:

  • Counting 4 beats per measure, i.e. “1, 2, 3, 4” on each quarter note. Bluegrass tempos often land in the 160-260 BPM range.
  • Counting 2 beats per measure, i.e. half notes, or what you hear the bass playing. Bluegrass tempos often land in the 80-130 BPM range.

Strum Machine opts for the second convention by default. Why? Because it was designed for bluegrass practice first and foremost, and that’s how I always heard people counting into songs at jams (“1, 2, 3, 4” spanning two measures). Besides, bluegrass is generally considered to be “felt” in cut time, with two beats per measure. That’s how you’d naturally tap your foot to a bluegrass song, for example.

That said, if you prefer to see quarter-note BPMs in Strum Machine, you can! Just go to the top-left menu in the app, then Advanced Settings, then set “Beats per measure in standard time” to “Four”.

Marcel Ardans has an in-depth video that explores this topic as well:

Thanks for the thorough explanation. This makes sense, and Marcel’s video is helpful too.

I think you might have reversed your examples above by the way. At 4 beats per measure you would have the higher bpm, not lower.

Glad that helped, and thanks for catching my mistake! (I edited my response.)