TOPS/W
Beginner
How many trillion math steps a chip does for each joule of energy. A joule is about what it takes to lift an apple one meter. Higher is better.
Novice
Tera-operations per second per watt, the same as trillions of operations per joule. One multiply-accumulate usually counts as two operations. 10 TOPS/W means 100 femtojoules per operation.
Expert
Meaningless without the precision, the sparsity assumed, what is included (array only, macro, chip, system) and whether it is peak or sustained on a real workload. Some papers normalize to 1-bit operations, which inflates numbers by the product of the bit widths.
Explained in Sparsity, in-memory and analog compute (Architectures).