Calculate tread depth, total tread count, and whether your tread meets code — the horizontal dimension that controls stair comfort and compliance.
The tread is the horizontal part of a step you walk on; its depth (the "going") is one of the two numbers that define a stair. This calculator focuses on the tread, using the same engine as the straight stair calculator.
The IRC requires 10 inches; the IBC commercial standard 11 inches; the Australian NCC 240 mm.
Always one fewer than the number of risers.
They are the same horizontal dimension; "going" is the British/Australian term.