How do I match a stand alone motor with a stand...

The VPI HRX or the standard VPI TNT V - motor together with the (I think ) indispensable SDS are a sure bet and will suit all platters if not the ones with outstanding diameter.
Sidssp gave the formula - it always a function of the RPM, and the two diameters - pulley (flywheel...) and platter.
Line voltage AC - better its related frequency - can be an issue if the correct motor speed is directly controlled by and founded on the AC line frequency.

The - good value for the money - SDS surely is a problem solver for these matters.

I have a clearaudio reference motor and a scheu table with a heavy platter. I will find out the details and update.
Thanks

Huh. I recently bought a VPI stand alone stainless steel motor for my "stand alone" table. Never did any calculations and it worked perfectly. I of course added their SDS for even better speed accuracy/stability but it sounded wonderful without. (I had another stand alone motor that had different pulley size and it worked too). Maybe I just got lucky?

Assuming the drive belt goes around the outside of the platter, you need to
know the RPM of the motor (R), the diameter of the pulley (d), and the diameter
of the platter (D); and make sure (R * d) / D = 33.33. If you have speed control
than it doesn't have to to be exact. A few percentage off is Ok.

Identical Voltage