For Greek yogurt: 8 cups of milk=4 cups of yogurt. The amount of milk is versatile. Due to draining off the whey, you'll need twice the amount of milk as you want yogurt. I just fill my container twice, and it's the perfect amount of finished product. For regular yogurt: 8 cups of milk=8 cups of yogurt. Your finished product is the same as the amount of milk you put in. You don't drain off the whey. In a large sauce pan, scald 8 cups of milk. Bring to ALMOST boiling, stirring constantly, to avoid scorching.
Take off heat and cover with a tea towel, until cool enough to keep your finger in comfortably for a few seconds. You don't want it too warm, or it will kill all your live cultures when you add your yogurt! Also, you don't want it too cool, or it hinders the growth of the live cultures, and takes longer for the yogurt to set.
Add your yogurt, to the warm milk, and combine well.
OPTIONAL: At this point, if you prefer, you can add your sweetener of your choice, and/or chopped, cooked fruit. Mix well. This may affect the texture of the yogurt, maybe not so smooth. ***OR you can omit one or both and just have plain yogurt. you can also add your fruit later. Cover with a lid or plastic wrap, and incubate (i.e.-let your little live cultures multiply) and if your house is warm enough, you can set it on a counter, or in the oven (don't turn the oven on)....just a warm place that the yogurt can set for overnight, or approximately 12 hours, undisturbed, or until the yogurt is set to your liking.Optionally, if you have a dehydrator, you can put it in, at 115℉ and let it set for 4-6 hours, or until the yogurt is set to your liking. To make regular yogurt: once the yogurt is set to your liking, you are finished! Put into storage container, and refrigerate.To make Greek yogurt: you will need to drain it--go to the next step. Put a large piece of cheesecloth, or a thin tea towel into a large colander, and put the colander into a large bowl, or pan large enough to catch the whey-- about half the amount of the milk you used. You are trying to drain it all off, so your yogurt is thicker.
Pour your set yogurt into the cheesecloth in the colander. Cover and put into the refrigerator for several hours, till all the whey is drained. Put into storage container and keep in the refrigerator.
Enjoy!
When you are just about out of yogurt, always save the last 1/2 cup or so to use in your next batch of homemade yogurt. Or if you forgot, you can always buy a small container of store bought to culture your next batch.