Have been performed the output factor measurements of the small square field with dimensions of 8 x 8 cm2 and smaller, for electron beams with energy of 6, 8, 10, 12, and 15 MeV. The experiments has been performed using the Elekta Synergy Platform Linac, solid water, the Exradin A11 plan-parallel ion chamber, Exradin A16 micro ion chamber, PTW Freiburg T60010M-4 silicon diode, and Gafchromic® EBT-3 film. The result described that the output factor of all detectors decreased with decreasing field size and energy electron beams. The comparison of output factor to output at reference condition for all detectors has discrepancy maximum in the range of 49.5-87.6 % on field 1 x 1 cm2 for 6 MeV, and a minimum value in the range of of 0.49-1.21 % on 8 x 8 cm2 for 15 MeV so it makes the dose distribution of electron treatment of square field of 1 x 1 cm2 were not appropriate for patient treatment. In this study, PTW Freiburg T60010M-4 silicon diode and Gafchromic® EBT-3 film demonstrated more compatible for small field electron beam measurement.