Wavelengths of light are perceived as color, and frequencies of sound are perceived as pitch; however, it is not known what properties of a molecule are perceived as smell. In this study, we are the first to show that the molecular volume of an odorant is an important factor in the fruit fly ( Drosophila ). Odorant molecular volume affects two dimensions of smell: intensity (weak or strong) and quality (sweet, floral, fruity, and similar factors). Molecular volume might explain the #scent differences between methanol and butanol, which are two similar molecules of different sizes. Methanol smells pungent, whereas the scent of butanol is similar to wine with a slight banana-like aroma.