The peak positions and halfwidths of the Q-branch of the ν1 band and the ratios of intensities of the Q-branches of ν3 and 2ν2 bands of methane are measured in a methane–helium mixture at different pressures and concentrations. An empirical model is developed for estimation of the He concentration in a methane-containing medium from measurements of the above parameters. The error in the He concentration is found to be less than 1% when using the ν1 band halfwidth. The paths of improvement of this technique and enhancement of its accuracy are considered.