This is a measurement of how many grams per millilitre something measures. 1 ml of water is one gram, which is our baseline. You may also see this as 1 cc or cubic centimetre. So 1 ml or 1 cc of water weighs 1 gram. This means that 5 ml or 1 teaspoon of water = 5 gram. (For a longer post, click here.)
If something is 1.03, it means 1 ml weighs 1.03 grams. If something is 1.35 it means 1 ml weighs 1.35 grams. If something is 0.90, it means 1 ml weighs 0.90 grams. Our oils are lighter than water, so if you have 10 ml of oils, you have 9 grams of oil. This means if you want 60 ml anhydrous facial serum, you need to use 54 grams of oil as 60 grams will be too much! This can mess you up when you’re teaching a class in which you’re making a 60 gram anhydrous facial serum that goes into a 60 ml bottle. 60 grams of oil.