The quality of various commercial silicon nitride raw powders was compared and evaluated. Various powder characteristics and sinterability of low-cost Chinese powders were compared with those of powders from advanced manufacturers. Powder characteristics such as particle size, agglomeration, impurity content, and β phase fraction, as well as bulk characteristics such as β phase fraction and sintered density were investigated. The Chinese powder showed characteristics that were inferior to the E10 powder from UBE, Japan in most evaluated characteristics, but were comparable to the powders from other advanced manufacturers. However, at high temperature sintering of 1,800 °C, the sintered density of the Chinese powder was noticeably lower than that of the other powders. The correlation between various powder characteristics and sintered density was also quantified using the Pearson correlation coefficient. In the 1,700 °C sintered specimens, the particle size and β phase fraction were found to have a strong negative correlation with the sintered density. In contrast, the 1,800 °C specimens did not show any powder properties with a strong correlation to the sintered density.