Extreme ultraviolet interferometric lithography (EUV-IL) is a powerful nanopatterning technique, exploiting the interference of two beams of short-wavelength radiation to form high-accuracy fringe patterns. Transmission diffraction gratings of appropriate period are used to form the beams; the substrate is located in the region of overlap to expose the photoresist material, recording interference fringe patterns. Although the physics of EUV-IL is simple, its actual implementation is not and requires attention to detail in order to fully exploit the power of the technique. In order to understand the impact of realistic physical conditions on the performance of EUV-IL, we have developed a set of accurate numerical models based on the Rayleigh–Sommerfeld diffraction theory. These modeling tools are then applied to generate a complete and accurate analysis of EUV-IL, taking into account all the relevant physical processes, from finite extent of the gratings to the partial coherence of the source, and including detailed physical structure of the mask. The results are used to guide the design and implementation of EUV-IL exposure systems, down to the sub- range.