4 c. cow’s milk
1/4 t. yogurt starter*
*More or less yogurt starter may be used depending on the brand of starter. Some brands use up to 1-2 t. per quart of milk. I use Natren Yogurt Starter and GI Pro Starter yogurt starter.
I put my yogurt in our oven with the oven turned off but the oven light turned on to warm the milk into yogurt. I have an inexpensive yogurt maker that works well, also. The yogurt needs to set in a warm place at about 90 degrees. I have also used a crock pot, a durable container with a lid with a heating pad inside (like a Rubbermaid container), just someplace warm where heat won't escape. I usually incubate my yogurt for about 7 hours for cow’s milk, but it depends on the brand of yogurt starter how long the yogurt needs to set. There are more expensive yogurt machines that will do the work for you, including the cooking time.
It is possible to make yogurt from existing plain yogurt instead of yogurt starter, but my batches always failed. I have had a positive result every time by using the yogurt starter. I am able to make organic yogurt for almost one-fourth of the cost of organic yogurt from the grocery store and one-half of the price of regular yogurt.