For what it's worth, there are *two* standards for relating dBFS to VU (and dBu.) From my studio days, I recalled using -18dBFS as my 0VU reference point.

However, a quick Google and perusal turned up both EBU R68 and SMPTE RP155, which define different VU/dBFS standards. Basically, omitting the rest of the curve, SMPTE likes to see -20dBFS == +4 dBu == 0VU, and EBU defines -18dBFS == 0dBu == VU.

Thus, the interested reader could choose either of those. Personally, I'll stick with EBU.