FWHM is an abbreviation for the full width at half maximum. It is a characteristic of a function or a graph curve and describes how wide the data distribution is. For instance, FWHM is used in chromatography to characterize the performance of chromatographic columns in a separation process. FWHM can be determined as the distance between the curve points at the peak half maximum level.
On a data graph, draw a vertical line from the peak maximum to the baseline.
Measure the length of this line and divide it by 2 to find the center of the line.
Draw a line passing through the line center and parallel to the baseline.
Measure the length of the line (Step 3) to find FWHM.