Okay--okay--I just limped out to the greenhouse in the dark LOL (knee problems) & measured for everyone. .From top petal to bottom of the lip 6" & from tip to tip of lateral petals also 6" so I would say 6" flower.
That is one large, beautiful flower. I have Blc. Keowee 'Mendenhall' and 'Newberry'. They flowers are similar but they don't compare to the size of that one.