The aim of this study is to compare various flow maldistribution quantification methods, namely using velocity, mass flow rate, pressure, and temperature. An experimentally validated numerical study has been prepared and a heat exchanger with 34 semi-circular channels made from aluminum with a diameter of 3.1 mm and a length of 120 mm has been tested. The minichannels were heated from the bottom with a constant heat flux of 10, 20, 30, and 40 kW/m2. Moreover, the cases for various inlet velocities of 0.1, 0.2, 0.3, and 0.4 m/s (that result in Reynolds number at the inlet of 995, 1990, 2986, and 3981 and mean Reynolds number in a single channel of 115, 230, 345 and 460 respectively) have been tested. It results in a total of 16 cases with various heat flux and various inlet velocities of the water. Then, for every 16 cases, the flow maldistribution coefficients, widely used in the literature, have been calculated based on the velocity, pressure, and temperature profiles in the minichannel heat exchanger. The study shows that every method gives other results of the parameter named “flow maldistribution coefficient” that should define the flow distribution in the entire heat exchanger in the same way. Hence, the ambiguities of fluid distribution conclusions in the minichannel heat exchangers that can be found in the literature may be caused by a different interpretation of the flow maldistribution coefficient. The paper shows the results in the most normalized manner to make them comparable and to draw clear conclusions on what is the relationship between fluid distribution, inlet velocity, and applied heat flux. Moreover, a normalized flow maldistribution coefficient that gives the same results for all thermohydraulic parameters used has been proposed.