Milk fat droplet, coloured scanning electron micrograph (SEM). The percentage of fat in milk various depending on the animal producing it. In humans and cows, the fat content of milk is around four percent. Fat droplets form a finely divided emulsion in the aqueous portion of the milk. Many substances, such as proteins and antibodies, are carried on fat droplets in milk. Over time, the fat droplets move upwards and form cream. This can be used to make butter, which contains more than 80 percent milk fat. Magnification: x20,000 when printed at 10 centimetres across.