A transformer is monitored by a dissolved gas monitoring device. A method in the form of executable code instructs a processor to estimate a remaining life of the transformer. The method includes receiving, from the monitoring device data elements representing a current value of dissolved gases in the transformer that correlate with degradation of insulating material in the transformer. Adjustment values are determined for the gases in response to isolated events occurring at the transformer. The current value and the adjustment values are combined to obtain a total value, and a degree of polymerization value is estimated using the total value. The value is converted into a measure of remaining life of the transformer, and the measure of remaining life is presented to a user.