Shimano Claris FH-2400 Rear Hub Dimensions
Details found here: http://productinfo.shimano.com/specifications.html

Spoke Hole P.C.D. Left/Right (mm) 45
Flange distance (mm) 57.9
Dish (mm) 8.4


Based on these figures, I would calculate the following values for your chosen Spoke Length Calculator:

Centreline to Left flange: 37.35mm
Centreline to Right flange: 20.55


Spoke hole diameter is not given.