Small form factor (SFF) refers to any of several physically compact connector designs that have been developed for use in fibre optic systems. They are about half the size of conventional connectors. Currently there are at least three designs: the LC by Lucent, the VF-45 by 3M, and the MT-RJ by Tyco.

The main motivator for the development of SFF connectors is an ongoing demand for smaller components in network systems. Using SFF connectors, it is possible to get many more interfaces on a single card. In addition, the use of connectors, rather than direct soldering, increases the flexibility and versatility of network systems, and makes it easier and less expensive to maintain them.

The fact that there are several SFF connector configurations allows the use of products from multiple sources. An argument has been made for standardisation, but individual connector makers have so far resisted this idea, preferring instead to develop and promote their own connector designs.