Q. How do I know how much oil I need to fill a mold?
A. One way to estimate how much a mold will hold is to measure the internal dimensions of your mold -
length x width x height x .4 will give you the ounces of oils that it should be in your recipe..
For example, a mold that is 18" long, 3.5" wide that is poured to 2.5" tall will hold 18 x 3.5 x 2.5 x .4 which is 63 oz. Which is close to 64 oz, 4 pounds.
When someone talks about a 3 pound soap recipe, they are usually referring to the amount of oils.