In one example, a device includes a video coder configured to determine a context for entropy coding a bin of a value indicative of a last significant coefficient of a block of video data using a function of an index of the bin, and code the bin using the determined context. The video coder may encode or decode the bin using context-adaptive binary arithmetic coding (CABAC). The function may also depend on a size of the block. In this manner, a table indicating context indexes for the contexts need not be stored by the device.