The area of a peak is proportional to amount of the compound that is present. The area can be approximated by treating the peak as a triangle. The area of a triangle is calculated by multiplying the height of
the peak times its width at half height.
IMAGE. A representative chromatogram.

For example, using a ruler, the Peak A was measured to have a height of 28.2 mm and a width at the halfheight of 3.5 mm. Peak B has a height of 41.2 mm and a width at halfheight of 4.5 mm. Therefore, the areas of the peaks can be calcuated as follows:
Using these areas, the percent of each compound in the sample
can be calculated.<
In addition, the ratio of B to A can be found using the areas.
