For epoxy use its much easier to stick with metric units for everything.If you know the weight of the cloth in grams/sq.metre and the number of square metres you need to cover,you can calculate the weight of glass.You should ai for a 1:1 ratio and allow for a little loss by absorption on you brushes and rollers.I don't understand quite how anybody arrives at an answer in gallons without knowing more about the viscosity of the resin.

There is a thread in another section about using plastic rowlocks,seek it out and read it before buying some.