Set your meter at 800, shoot the roll. Unless you use a developer like Acufine, once you select a developer add 50% to the base time for each push. So if you are using D76, ID11 at 7.5 add 3.75 for a toatal of 11.25. If you want to push 2 stops to 1600 you add another 50% or 5.6 to the 11.25 for a total of 16.85 or just round up to 17.