Abstract: A method of deducing time based metrics using flow rate is disclosed. The method uses a thermal mass flow meter wherein the meter comprises a pipe housing and a sensor board with at least one heating element and at least two temperature sensors is located inside the pipe and where a microprocessor is programmed to calculate a flow rate based on a logarithmic function of difference between base line temperature difference between temperature sensors before heating element is turned on and a second temperature difference between the temperature sensors after heating element is turned on. Duration of gas supply is provided by using the measured flow rate and information of the gas supply.