Bulk, single grain (RE)Ba2Cu3O7- [(RE)BCO, where RE is a rare earth element or yttrium] high temperature superconductors (HTS) exhibit much potential for use in a variety of engineering applications due to their ability to trap large magnetic fields; the fields trapped can be up to 10 times greater than those generated by conventional magnets. Limitations on the maximum single grain which can be grown are a major obstacle to the further development of these materials. Indeed, multiple samples are often required to achieve the required superconducting properties in applications. The geometry of bulk (RE)BCO single grains samples play an important role in determining the superconducting properties of a given arrangement. In order to gain a better understanding of the full applications potential of bulk single grain superconductors three, relatively long, cylindrical YBCO single grains of different diameters were fabricated and their trapped field and total trapped flux measured at 77 K as a function of sample height. The effects of size and aspect ratio of YBCO single grains on these key applied properties have been investigated experimentally and the results compared qualitatively with the predictions of an established model. Conclusions based on the trapped field measurements on a variety of single grain samples are presented in this study and the possibilities of using assemblies of smaller samples for engineering devices, in particular, are discussed.