In most cases, stylists mix equal amounts of developer and hair pigment. For example, if 2 ounces of pigment is used, 2 ounces of developer is added to activate the pigment. Sometimes, such as in high-lift applications, a higher ratio of developer to color is used.
For most applications, 4 ounces of hair color, consisting of 2 ounces of developer combined with 2 ounces of pigment, is enough to color all the hair. However, it may take 6 to 8 ounces to color hair that is particularly thick or long. Since hair color is only good for about an hour, it's usually mixed as needed rather than all at once.