TRYING ON A FRIENDS  LETTER JACKET THEN LOOKING AT THE LABEL FOR THE SIZE IS A REASONABLE METHOD TO FIND A FIT. 
TRY NOT TO RELY SOLELY ON A CHART. 
This chart measures the jacket outside dimensions and isn't really a good method to fit. Inside will vary with different lining options.

Caution. These are the actual jacket outer shell manufacturing measurement specifications, not your body measurements.
A -Sleeve length (From collar seam to end of sleeve including the shoulder and cuff).
B -Shoulder width (The length between the two shoulder seams)
C -From the collar seam to bottom of waistband
D -Waist size (Jacket Waistband circumference)
E -Chest size (Jacket Chest outside Circumference*)

All measurements are in inches. 1 inch = 2.54 cms.

*Jacket Measurements are a guideline only and no guarantee is implied.  Try on a friends and look at label to determine manufacturer. Then, let us know.
Jackets are custom made to your order,  not custom fitted *.
Normally, we don't recommend up sizing adult sizes as jackets are full cut. However, please consider you may wear additional garments like hoodies, sweaters and uniforms  under your jacket as well as allowing for growth. Also allow for quilted lining to affect sizing and add bulk. This is especially noticeable in smaller adult and youth sizes. You may want to try on another student's jacket. All measurements in inches.
Caution for youth sizes: quilted lining in small jackets can make both the body and sleeves feel too tight. We recommend standard non quilted in youth jackets.
   
 APPROX
WT
 APPROX
WT
 APPROX
WT
 APPROX
WT
 APPROX
WT
 APPROX
WT
  
  ADULT JACKET
UNISEX MEASUREMENTS
120-130 LBS
  145 LBS   175 LBS
  200 LBS
230 LBS
260 LBS
  
MEASURE IN INCHES   S M L XL 2XL XXX 4XL
SLEEVE A 33-35 36-38 36.5 37.25 38 38.5 40
SHOULDER B 24.5 25 25.5 26 26.5 27 28
BACK C 27 27.5 28 28.5 29 29.5 30
WAIST D 30 32 34 36 38 39 40
CHEST CIRCUMFERENCE' E 50* 52* 54* 56* 58* 60* 62*
CUFF   3.25 3.5 3.75 4 4.25 4.25 4.25
                 
  LADIES JACKET  SIZE MEASUREMENTS *OPTONALLY AVAILBLE FROM 1 FACILITY ONLY*
              
INCHES  **********LADIES TEMPLATE NOT LONGER OFFERED**** S M L XL 2XL XXX 4XL
SLEEVE A 33.5 34.25 35 35.75 36.5 37.5 38
SHOULDER B 23.5 24 24.5 25 25.5 26.5 26
BACK C 26 26.5 27 27.5 28 28.5 29
WAIST D 26 28 30 32 34 35 36
CHEST E 46* 48* 50* 52* 54*
56*
 58*
CUFF F 3 3 3.25 3.5 3.75 3.75 3.75
                 
                 
  YOUTH  ASK
 YS
 YM
 N/A
 YL
  YXL  AXS
YOUTH APPAREL SIZE
 
2-4
6-8
10-11
12-13
14-15
16-18
20
SLEEVE A 25.5 26.75 28 29.25 30.5 32.00 33
SHOULDER B 19.5 20 20.5 21 21.5 22 22.5
BACK LENGTH C 19 20 21 22 23 24 25
WAIST D 20 21.5 23 24.5 26 28 30
CHEST E 32 34 36 38 40 42 44
CUFF F 2 1/4 2 3/8 2.5 2 5/8 2 3/4 2 7/8 3
                 

*NOTE*
*Jackets may vary in finished size from one (1) inch in smaller sizes to +/-2 inches in sizes XX up.
This is due to pattern sew.
Jackets are full cut and custom made not custom fitted. 

We use the same sizing templates as many other USA  and international Letter Jacket suppliers.

Youth AND SMALLER SIZE jackets with quilted/insulated lining may feel tight.