Recently, the diesel engine particulate matter (PM) emission standard was changed from being based on mass to being based on both number and mass. However, it is difficult to determine the mass- and number-weighted distributions simultaneously because of the complex shapes of PM. We studied a new method to determine the mass-weighted distribution of PM using the primary particle density, and compared it with two conventional PM measurement methods using effective density and gravimetric filtration. In the method developed, the primary particle size was measured using transmission electron microscopy (TEM)-calibrated laser-induced incandescence (LII) to detect changes in the primary particle size in real-time. The number-weighted distribution of aggregates was measured with a scanning mobility particle sizer (SMPS). The mass-mobility exponent and the effective density were determined with an impactor and the SMPS. The differences in the mass concentrations for each technique were between 3.1% and 29.9%. (C) 2011 Elsevier Ltd. All rights reserved.