Handmade soaps are made by hand. They are not made by machines that perfectly account for humidity, oil weight, water density and so forth. They are formed in open loaf molds (like a meat loaf pan) that can tip one way or the other or fill slightly more from one side to the other.
We do everything we can to ensure that every bar of soap is as close to the same size as possible, but hey, we're humans. Sometimes our soaps vary in size but always fall within the range of 3.75 ounces and 4.25 ounces.
If you have any questions about this or anything else, please contact us.