Nanocellulose extracted from renewable sources, is a promising reinforcement for many polymers and is a material where strong interfibre hydrogen bonds add effects not seen in microfiber composites. Presented is a tool for comparing different nanocellulose composites based on estimating the efficiency of nanocellulose reinforcement. A reinforcing efficiency factor is calculated from reported values of elastic modulus and strength from various nanocellulose composites using established micromechanical models. In addition, for the strength, a network model is derived based on fibre-fibre bond strength within nanocellulose networks. The strength results highlight the importance of the plastic deformation in the nanocellulose composites. Both modulus and strength efficiency show that the network strength and modulus has a greater effect than that of the individual constituents. In the best cases, nanocellulose reinforcement exceeds all model predictions.