Each one of the four cups of wine that we drink at the Seder must hold a halachik liquid measure known as a revi’is. When converting that to ounces we follow the view that a revi’is is 3 fl. oz.
However for Kiddush that we recite on Friday night the cup should hold 4.4 fl. oz. This is because the recital of Kiddush that we make every Friday night is the fulfillment of a Torah obligation to declare Shabbat as a holy day. In this case we follow the view that the revi’is should be larger.
Therefore this year when the Seder night is Friday night we should make sure that the first cup should hold 4.4 fl.oz. (the other three could be smaller and hold 3 fl. oz.).
Regarding how much wine to drink, the order of preference is:
1) Drink the entire cup even if it is larger than a revi’is .
2) Drink the majority of the cup even if it is larger than a revi’is.
3) Drink a revi’is.
4) Drink the majority of a revi’is.
For this year, calculate the revi’is for the first cup as 4.4 fl. oz.
Chag kasher v’samayach- a kosher and joyous Passover!