I highly recommened purchasing a program such as ICMizer or holdemresourcescalculator.

As far as calculating things manually, this may help.

Calculating a shove-


situation is bb= 100 and hero is on the button with 98s

General estimate is that villains in Sb and bb will be calling with ~20%. Enter in 89s vrs 20% in pokerstove or http://www.propokertools.com/simulations
and you will see we have 36.6% equity when called.

Hero has 1k at bb= 100

Effective stack - 1000

Estimated equity when called = 36.6%

Pot size= 150 (bb+sb)

Facing bet - 100 (the bb folding around to us)

If input properly, you will see that villain needs to fold 63% of the time

In calculating how often we are getting called since we are shoving into two opponents and not just one. Multiply the %'s of the time they are folding by
eachother. So for example, since we have both villains calling 20% of the time, they are folding 80% of the time each. You do .8 x .8 = 64%. They
only need to fold 63% of the time, therefore this is a profitable shove.