Still inches. But most airliners and larger aircraft use approved weight and balance programs that use "zones" to facilitate faster computations. The CRJ I flew had 4 zones: A, B, C and cargo. I don't remember specifically, but zone A was something like rows 1-4, B: rows 5-8, C: rows 9-13.

The FA counted passengers in each zone, and we used a "whiz wheel" to spin the numbers and figure out if we were in limits or not.


(the calculator has two other layers not depicted that allowed us to move stuff into the computation on the top half that resulted in a change on the bottom half)