Unlike traditional drift-tube ion mobility-mass spectrometry, traveling-wave ion mobility-mass spectrometry typically requires calibration in order to generate collision cross section (CCS) values. Although this has received a significant amount of attention for positive-ion mode analysis, little attention has been paid for CCS calibration in negative ion mode. Here, we provide drift-tube CCS values for [M - H](-) ions of two calibrant series, polyalanine and polymalic acid, and evaluate both types of calibrants in terms of the accuracy and precision of the traveling-wave ion mobility CCS values that they produce.