No, amount ratio. Means for every F seat I'd have 6 Cs and 42Ys.

I also use size ratio to measure the space needed in the plane.

SF=4F, SC=2C, SY=Y (F, C, and Y are the number from the ratio. F=1, C=6, Y=42).

Then I make my own formula that the total number of seats for each class is the number of its ration times my desired capacity divided by a number (x) which I think should mean the space needed for each seat (but I don't know since who cares).

**Example**: Boeing 777-200 with 440 max pax

To provide legroom, I will only use 85% of the maximum capacity, so 0.85 x 440 = 374

Since I will have three classes, then SF+SC+SY = 4x1 + 6x2 + 1x42 = 58

Then I look for the (x) which (x) = 374/58 = 6.45

Last, I bring the (x) number to the seating ratio, then choose some closest round numbers around it. So...

F = 6.45 x 1 = 6.45 (6 seats)

C= 6.45 x 6 = 38.7 (38 to 40 seats)

Y= 6.45 x 42 = 270.8 (268 to 272 seats)

*Another Example*: Airbus A320-200 with 180 max pax

85% x 180 = 153

I'm only gonna have C and Y class so SC+SY = 6x2 + 1x42 = 54

(x) = 153/54 = 2.83

C = 6 x 2.83 = 17 (16-18 seats)

Y = 42 x 2.83 = 119 (118-120 seats)

This, obviously, is not realistic cabin config and only an effort to max profit from each class' demand.

Then, again, there's always someone with full Y seats competing for your routes so at the end of the day I always wonder why I even bother doing the counting.