Pyrotechnic compositions based on magnesium, teflon, (MTV) have many desirable properties for use as igniters for solid rocket propellant. Safety and reliability include low hygroscopicity, easier ignitability, good grain fabrication, stability during burning, and low production costs. This study produces a novel method for designing MTV igniters based on the thermochemical properties of the compositions. A theoretical study has been carried out using the NASA CEA program for modelling the combustion properties for different MTV compositions with different fuel-to-oxidizer ratios (F/O), which vary between 0.18 and 3.75. The study investigates the effect of the (F/O) ratio on the heat of combustion, which decreases with increasing the (F/O) ratio. The output values of the NASA CEA program are the main parameter for the novel method to determine the mass of the MTV igniter for the required rocket propellant. The study concluded that as the F/O ratio increases, the required mass of the igniter increases.