The seder is the only time in the year that you must drink most of your cup (rov kos) of kiddush wine. (For kiddush on Shabbat and Jewish festivals, you need drink only 2 fl. oz., or 59 ml).  So if you have a cup larger than 4 fl. oz. (119 ml), you may have to drink a lot of wine--more than half of each cup for four cups!