4F- Memory cell sizes are measured using an nF² formula where ‘n’ is a constant derived from the cell design and ‘F’ is the feature size of the process technology. For example, in a 130nm process node, F = 0.13 micron, and therefore 4F2 = 4 x 0.13 x 013 = 0.0676 square micron. For the same feature size, as the cell size becomes smaller, memory capacity increases.