I make the vests one at a time to fit the dog.

I need:

   A.  Width across the top of the front leg at the shoulder
           (for the width of the vest)
    B.  Over the back from the top of one leg to the top of the other
           (for the length)
    C.  Girth - all the way around just behind the front legs
           (for the back strap)
    D.  Across the chest from shoulder to shoulder
           (for the front strap)
    E.  From side of neck -- where the collar rests -- to the tip of the nose
           (for how far out the halo needs to go)
Measurements
For example, Scooter, Miniature Schnauzer, was A=4", B=12", C=21", D=7", E=8"
His vest was 5" wide and 12" long.
NOTES:
* Big Dogs -- E greater than 12"
    not recommended (click button to find
                                  out why)

* Use a tape measure for B & C;
        a ruler for A, D, & E

* B is usually about 60-70% of the girth (C)

* For E, keep the head in a normal postion
        -- do not stretch the neck
Numbers that might help
MEASUREMENTS (INCHES)
general sizesA          B           C          D          E    

SMALL         2-4       6-10      10-17      4-6       5-8

MEDIUM       3-5     10-14      18-23      5-8      6-10

LARGE         5-6     14-18      24-29     6-10    8.5-12

X-LARGE *    7-8   18-21.5     30-36      8-13      12 +
  (not recommended)

USE "C" TO DETERMINE SIZE