The Hub dimensions are on the product pages and lasered onto the center of the hubs.
PCD stands for Pitch Circle Diameter and refers to the distance between opposing spoke holes on the hub flanges (from the center of the hole).
Flange Dist refers to the distance from the center of the flange to the center point of the hub.
L stands for Left & R stands for right.
These four measurements, along with your hub spacing (110 or 148mm) and the ERD of your rim is all you need to measure spoke length. Please use your preferred spoke calculator to complete the measurement!