2 gallons last time
I've done mine 3 times with Trinidad. Each time I bought 3 gallons, each time I had some left. The last time I reaized I was sanding off a lot of very good paint, so I only put it on heavy where it actually was used up, which was mainly around the water line. On the parts that point down, it was still nearly as thick as when I put it on. Once I finished, I still had one unopened gallon can.By the way, each time it was about 5 years between bottom jobs.