That would depend on the purity of the heroin to begin with, and the desired purity after cutting it. An example might be a qty. of 80% pure heroin. Take 10 grams of 80% pure heroin for example, add 5 grams of Dormin or other cut to the 10 grams of heroin to get 15 grams of 60% pure heroin. Mixture must be done properly, ensuring even distribution of cut and heroin. You can do a simple mathematics equitation to figure out the amount of cut needed if the purity of the starting heroin is known that is..or use an online mixture calculator...This all relies on having a known purity of heroin or whatever drug you want to cut though, otherwise you are just guessing and could ruin the quality of the heroin you are trying to cut...