Comparison among methods for calculating FWHM

Abstract Five methods for calculating full width at half maximum (FWHM) are presented and applied to computer generated pseudorandom normal distributions of known parameters. The methods employ: the definition of FWHM, the relation between FWHM and the area under a Gaussian, the second moment of the peak, least-squares fit of the logarithm of the distribution to a parabola, and a least-squares fit to a straight line using the logarithm of the ratios of consecutive and equally spaced points on the Gaussian. The dependence of the error in the calculated FWHM on the Gaussian parameters - amplitude, mean and variance - is presented and discussed for each method. A comparison among the methods shows the superiority in accuracy of the second-moment method.