You approximate. Look at the surface you want to cover, think about how much you want over that whole surface and guess how much you will need. It is not a problem to under estimate, because you can always mix up more. It is a problem to over estimate because you will waste material and bigger batches "kick-off" faster so you may have to throw some out even when you are not done using it.

Start out with one pump of each and see how far it goes. This will give you an idea how much you need to finish the job.

> This seems like such a fundamental question that it has probably been
> addressed before. I have laid out the hull panels for my Chesapeake 17'
> and I am ready to begin epoxying the skarf joints. I am using the MAS
> metered pumpsystem that came with my kit. How much epoxy should I mix for
> this job? And as long as you experienced guys are at it, how do you guage
> how much to mix for the other jobs like the hull fillets, and coating the
> hull, and attaching the deck... ?