Each cone has a number assigned to it that corresponds to a specific temperature range.
The cone system measures how hot the kiln is and how long the clay body is fired in the kiln. Cones are essential when firing so that you know when your kiln has reached the necessary temperature and if the kiln was evenly heated. Each cone has a number assigned to it that corresponds to a specific temperature range. For example, cone 03 indicates a temperature range of about 1960 to 1987 degrees Fahrenheit.