There isn't _A_ formula. Everything deflects under load. Predicting how far an object will deflect requires knowing the geometry of the object, the geometry of the loading, and certain properties of the material from which the object is made.
The acronym CRS tells us something about the material, but we know nothing of the remainder of the problem. To answer your specific question, you will need to review beam theory, or find someone who doesn't need to.
One comment: CRS would an appropriate material only for extruding wax.
Mike Halloran
Pembroke Pines, FL, USA