Warhammer unit sizes?

[Mr Smit]

What is the correct/optimal/asthetic unit proportion to use in Warhammer FB, for archers/thunderers and warriors?

10-18 archers would be 2 ranks? 2x5 up to 2x9

21 or 24 archers would be 3 ranks? so 3x7 or 3x8

4x6 would be wrong surely as they are a distance unit they would want a thinner line for coverage and nor need much depth

Warriors?
18 would be 3x6?
24 would be 4x6?
32 would be 4x8?
40 would be 5x8?
48 would be 6x8?

what about 20/21 20 4x5 looks too square, 21 3x7 is that too long and thin?
I know extra ranks gives steadfast but surely number one is the width, as in 2 more attacks from 3x8 than 4x6

[Brian]

Small units of ranged troops benefit from being only two deep. Thunderers work best this way. Larger units, such as Wood Elf Glade Guard, are often used in deeper formations, as they can usually volley fire. In most armies, really wide ranged units are a bad idea, as they can be cumbersome to maneuver and are killed easily once engaged in close combat.
With melee oriented troops, such as Warriors, the real question is what are they fighting against? Generally, this will be similar troops ranked up 5 wide. With 20mm bases (the smaller ones), you will either want to go 5 wide to minimize casualties, or 7 wide to maximize offense. For troops on the larger, 25mm bases, 6 wide is pretty much ideal.
Keep in mind that you can reform your units during the game. If your 10 wide Thunderer unit is about to be charged, you can just form up 5 wide (during your movement phase) and have double the ranks of bonus.

tl;dr - Thunderers/Quarrelers = 10, Warriors = 28 (assuming you mean Dwarfs).