Due to the shortage of data regarding range and water equivalent ratio (WER), in this work, firstly, depth-dose profiles and range were evaluated in liquid water, Polyethylene (PE), Aluminium, Bone, Polymethyl methacrylate (PMMA), and Lead for carbon ion energies ranging 100–300 MeV/n using Fluka Mc code. Afterwards, persuing the repeated use of the above mentioned materials in dosimetric studies in the domain of hadrontherapy, we came up to calculate the water equivalent ratio of only three dosimetric materials (polyethylene (PE), polymethyl methacrylate (PMMA) and lead). Then, we made the remark that the closest and farthest WER values are 1.0016 and 5.7939 respectively, they were obtained for the PE and the lead. The calculated WER values were compared with the values from MCNPX code, and those from the previous analytical methods (NM, BK, BB, EBB). Good agreement was obtained between the results of the MC codes and the previous analytical methods. The largest discrepancy between the two MC codes was 4.2% for PE at 100 MeV/n and was about 1.52% between Fluka and the analytical method (BB) for Lead at 270.83 MeV/n. Among the materials explored, PE stayed the nearest to water with an average WER of 1.0038 for carbon ion energy ranging 100 to 300 MeV/n.