Cigarette draw resistance and filter pressure drop (PD) are both major physical parameters for the tobacco industry. Therefore these parameters must be measured reliably. For these measurements, specific equipment calibrated with PD transfer standards is used. Each transfer standard must have a known and stable PD value, such standards usually being composed of several capillary tubes associated in parallel. However, PD values are modified by ambient conditions during calibration of such standards, i.e. by temperature and relative humidity (RH) of air, and atmospheric pressure. In order to reduce the influence of these ambient factors, a simplified model was developed for compensating the effects of ambient conditions on the calibration of multi-capillary PD standards.