What is the rule of thumb for calculating DENSITY ALTITUDE?

The rule of thumb for calculating density altitude is to add 120 feet to the pressure altitude for each degree above standard temperature. For example. If you pressure altitude was 700 feet and the temp was 28 degrees Celsius you would add 1560 feet to your pressure altitude giving you an approximate density altitude of 2260 feet. Remember high temperatures, high humidity, high altitudes, and low pressure all contribute to raising the density altitude.