Please consider the below points first:
* Monthly Total Expenditure of the Factory (MTE):
Suppose – BDT. 5,000,000.00
This expenditure is included of the below items:
a)     
Factory Rent, 
b)     
Commercial Cost, 
c)      
Electricity Bill, 
d)     
Water Bill, 
e)     
Transportation cost, 
f)      
Worker and Staff wages (8 hours/day – WHD), 
g)     
Miscellaneous cost, etc. 
* Number of Running Machine of the factory (NRM) of the
following month (which total expenditure need to be considered here).
Suppose – 100 machines.
* Number of machine to complete the layout (NML) for the
relevant item. Suppose – 25 machines.
* Hourly Production Target/Capacity (PCH) of the relevant
item, excluding alter & reject. Suppose – 200 pcs.
* Total
working day (TWD) of the relevant month. Suppose – 26 days.
* If the CM needs to be converted in US$ , then
conversion rate (CR) would be 1 US$ = BDT. 75.00
The Formula of Cost of Making:
CM = [{(MTE / TWD) / (NRM / NML)} / (PCH x WHD)] x 12 / CR)}
The Calculation will be as below:
CM = [{(5,000,000.00 / 26) / (100 / 25)} / (200 x 8)] x 12 / 75
CM = US$ 4.81 / Dz
CM = US$ 4.81 / Dz
MTE 
(in BDT.) 
 | 
  
TWD 
(Days) 
 | 
  
NRM 
(unit) 
 | 
  
NML 
(unit) 
 | 
  
PCH 
(pcs) 
 | 
  
WHD 
(hours) 
 | 
  
Dozen 
(pcs) 
 | 
  
CR 
(BDT.) 
 | 
  
CM/Dz 
(in US$) 
 | 
 
5,000,000.00 
 | 
  
26 
 | 
  
100 
 | 
  
25 
 | 
  
200 
 | 
  
8 
 | 
  
12 
 | 
  
75 
 | 
  
$4.81 
 | 
 
But after starting the new salary scale in Bangladesh, the CM might be
calculated by considering the overhead sewing machine cost as below:
* For a Non-compliance Factory:
To be considered the overhead sewing machine cost (OSMC) @BDT. 1,400 to 1,600.00 per day.
To be considered the overhead sewing machine cost (OSMC) @BDT. 1,400 to 1,600.00 per day.
* For a Compliance Factory:
To be considered the overhead sewing machine cost (OSMC) @BDT. 2,000 to 2,400.00 per day.
To be considered the overhead sewing machine cost (OSMC) @BDT. 2,000 to 2,400.00 per day.
So, if any factory produces any item 200 x 8 = 1,600 pcs per day by using
25 machines, then the CM will be as below:
* For a Non-compliance Factory:
  CM = {(OSMC x 25 /
1,600) x 12} / 75
  CM = {(1,600 x 25 /
1,600) x 12} / 75 = US$ 4.00/Dz
        * For a Compliance Factory: 
  CM = {(OSMC x 25 /
1,600) x 12} / 75
  CM = {(2,400 x 25 /
1,600) x 12} / 75 = US$ 6.00/Dz
---- x ----