In order to compare the densities, heats of formation, detonation velocities, and detonation pressures of the energetic pentazolate salts at the same level, density functional theory (DFT) method was used to study the sixteen N₅ˉ based nonmetallic energetic salts synthesized in the past two years. According to the Born-Haber energy cycle, the calculated heats of formation of the pentazolate salts are between 95.2 kJ·mol^-1 and 1362.0 kJ·mol^-1 at the MP2/6-311++G(d,p) level. The average heat of formation of the salts formed by the triazole-containing cation and N₅ˉ is the highest among the five types of N₅ˉ salts. The densities(at 298.15 K) of these pentazolate salts range from 1.395 g·cm^-3 to 1.650 g·cm^-3, which are much lower than the theoretical densities of all-nitrogen compounds. The detonation velocities and detonation pressures calculated by the Kamlet-Jacobs formula agree well with the calculation results from EXPLO5. Most of the N₅ˉ-containing ionic salts have detonation velocities between 6500 m·s^-1 and 8000 m·s^-1 and detonation pressures between 15 GPa and 26 GPa, which are lower than RDX. The theoretical detonation performance of biguanidinium, hydroxylammonium, and hydrazinium pentazolates are outstanding. Their detonation velocities (8622-9032 m·s^-1) are equal or slightly higher than that of RDX, and their detonation pressures (29.5-32.3 GPa) are lower than that of RDX. Thus, their predicted performance are not revolutionary. They do not exhibit the distinct advantages of all-nitrogen anion derivatives, and are far from the expectation of their ultra-high energy.