Computational results for the cumulative effect of ionizing radiation are presented for CubeSats taking into account the presence of trapped charged particles in the Earth's magnetosphere, protons and heavy ions from the Sun, and the cosmic rays. In contrast to relatively larger satellites, CubeSats are often launched with minimal shielding structures. Therefore, detailed modeling of a CubeSat is performed based on currently available standard platforms. The geometrical modeling is then used for an estimation of the ionizing doses for various locations within the CubeSat spacecraft operating at low altitudes. The calculation is reiterated and extended for more exotic orbits, such as geostationary Earth orbits and lunar orbits, for the potential application of CubeSats in challenging space missions. (C) 2012 Elsevier B.V. All rights reserved.