((Tanks x 2) + turrets + (troops /2)) x weapons x def bonus x gov bonus

Then add 1/4 of your def allies (to a maximum of the previous calc only)

Add 10% on top of all that for the 99% chance of no mehul factor.

/ weapons tech / gov bonus / 1.5 (if PSing)

And I usually send 2000 jets more just to put it over the edge.