Online fashion retailing is a major growth area. Innovative online fit and sizing technologies that facilitate purchase continue to develop and launch, however, problems associated with digital expectations of fit and size in consumer decision-making, remain unresolved. This research focuses on 20 prominent fit and size technologies from a sample of 30, and uses content analysis to examine website design and operation. Content analysis combined with an extended literature review enables the linking of academic theory and practice. The research provides discussion for best-practice utilisation of fit and sizing technology through the Omni-fit model, which accounts for the combination of technological approaches, and the emerging influence of augmented and virtual reality fashion technology. The results include the need for improvements to 3D visualisation, user experience, and online customer relationship management of existing websites, aligned with Omni-channel retailing practice.