I don't measure the humidity in the incubation containers. I dampen the vermiculite and as long as no more than a couple of drops of water can come out of it when you take a hand full and squeeze it...then it will be the right humidity. Once the lid is put on the container, there will be beads of moisture on the lid and the sides of the container....and that's okay. If you have the lid off too often during the incubation to check on the eggs or you make holes in the container that are too big, you may have to add a few drops of water during the incubation...but I don't usually have to do that.