Port Lavaca is located at 28°36'51" North, 96°37'32" West (28.614444, -96.625556).
According to the United States Census Bureau, the city has a total area of 13.64 mi2 (35.32 km2). 9.79 mi2 (25.34 km2) of it is land and 3.85 mi2 (9.98 km2) of it is covered by water. The total area is 28.24% water.
Port Lavaca is located in the Central Standard Time (CST) timezone, GMT-06:00. It observes Daylight Saving Time (DST).