For upward pressure calculation, you need the depth of the foundation. You see, upward soil pressure goes in increasing with increasing depth of the foundation because it takes into account the overburden soil. The method is already given in your attachment.
Upward pressure = ρD + W
Where: ρ: soil density, D: depth until the top face of the foundation, W: the weight of the foundation
It doesn’t require the knowledge of Safe bearing capacity. The upward pressure can be lesser than the SBC depending on the situation. If it is more than the foundation is unsafe.