How long will my braided bread be?
A contribution to predicting the length a braided loaf will have
In bread braiding, given a certain amount of dough the hitherto still unsolved problem is how to control de size of the finished product.
The final dimension of a simple loaf of bread is not so hard to manage; braiding that same amount of dough however, introduces a new unknown factor into the equation. Braiding a rope shortens its length since it has to traverse other ropes diagonally in the procedure. Proofing the braided dough increases its volume, as does oven spring.
Given a certain amount of dough, your choice and the size of your oven trays determines the length the braid should have.
Choice includes the number of ropes you choose to employ and the method for braiding them; there is more than one way to make braids with more than 3 ropes and results vary according to the technique used.
A composite of shrinking due to braiding, expansion of proofing and oven spring results in the following percentages of length diminution from rope to finished bread
Number of ropes  %
 Technique Used for Braiding 
3  24  http://www.youtube.com/watch?v=YR6aIAh2Vt8 [1]

4  19  http://thebakersguide.com/howtobraida4strandchallahbread [2] 
5  26  
6  23  http://chaitimeblog.wordpress.com/2006/09/03/videobraidingasixstrandchallah/ [4] 
Consequently, once you decide how long your braided bread should be, the ropes you roll should be longer in the corresponding percentage.
The amount of rope tension while braiding is another factor that influences the outcome.