Raw OPSS data for manuscript "Calibration of optical particle size spectrometers against a primary standard: Counting efficiency profile of the TSI Model 3330 OPS and Grimm 11-D monitor in the particle size range from 300 nm to 10 μm" Authors: Konstantina Vasilatou, Christian Wälchli, Stig Koust, Stefan Horender, Kenjiro Iida, Hiromu Sakurai, Friedhelm Schneider, Jürgen Spielvogel, Thomas Y. Wu and Kevin Auderset https://doi.org/10.1016/j.jaerosci.2021.105818 6 OPSS units (2 Grimm 11D and 4 TSI 3330) were calibrated during the study (see manuscript for more details). Here, we upload the raw data for only 5 units. The calibration of the TSI 3330 unit 4 was provided as commercial service and the data belong to the owner of the instrument. We also provide the excel spreadsheet for Figure 4 of the manuscript. For Figure 5, see respective excel spreadsheet.