Generally we refer to props by their diameter. So a 2 foot blade will produce a 4 foot prop, plus a bit for the hub area. I can see where it is confusing but most references to power versus prop are by diameter. Swept Area is the area inside the circle made by the prop tips going around and it is the Holy Grail of turbine power output. There is no substitute for swept area.

Hope that helps more than a sharp stick in the eye.

Tom