A monodisperse nanoparticle sample of polystyrene has been employed to determine performance of the 36 meter small‐angle neutron scattering (SANS) BATAN spectrometer (SMARTer) at the Neutron Scattering Laboratory (NSL)—Serpong, Indonesia, in a very low scattering vector q‐range. Detector position at 18 m from sample position, beam stopper of 50 mm in diameter, neutron wavelength of 5.66 Å as well as 18 m‐long collimator had been set up to achieve very low scattering vector q‐range of SMARTer. A polydisperse smeared‐spherical particle model was applied to fit the corrected small‐angle scattering data of monodisperse polystyrene nanoparticle sample. The mean average of particle radius of 610 Å, volume fraction of 0.0026, and polydispersity of 0.1 were obtained from the fitting results. The experiment results from SMARTer are comparable to SANS‐J, JAEA ‐ Japan and it is revealed that SMARTer is powerfully able to achieve the lowest scattering vector down to $\text{0.002\hspace{0.17em}}{\mathrm{\AA }}^{\text{−1}}.$