There are instructions included with the kit explaining how to mix up the concentrates into each of the working solutions. It results in 5L of each developer,bleach,fix, and stabiliser. What I do with this kit is make it up 500ml at a time and use that 500ml for a few rolls over the course of a couple of weeks, then dump it and make up another 500ml. This is accomplished by simply using 1/10th of each of the concentrates when making up the working solution. You need a measuring syringe for this, some of the amounts involved are pretty small. I top up the concentrates with protectan.