How do you calculate synergies to break even, and how do you use it in a pitch?

First calculate the EPS dilution before synergies. Convert the EPS gap into net income required by multiplying by pro-forma shares. Gross it up for tax to get pre-tax synergies needed. In a pitch, compare required synergies to management's synergy estimate. If break-even requires only a small portion of identified cost synergies, the deal has a stronger accretion case.