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Spooling Capacity Formula

Do you need to know how much cable your drum will spool?  This handy formula will show you how to calculate that amount.

Before you begin you will need four dimensions. 

The drum length (distance between the flanges) which is designated "B" on drawing below. 
The flange depth (from the top of the flange to the drum) which is designated "A" on drawing below. 
The drum diameter which is designated "D" on drawing below. 
The diameter of the cable.  When you know the diameter of the cable, use the chart below to determine the value of that diameter.  That value is designated "K".

The spooling capacity of your drum will be determined by the following formula:

SPOOLING CAPACITY =  (A + D) x A x B x K
First, add together the flange depth (A) and the drum diameter (D).  Multiply that number by the flange depth (A).  Multiply that number by the drum length (B).  Multiply that number by the value of the cable diameter (from chart below).  The product will be the spooling capacity of the drum.  Note:  to obtain the drum diameter, measure the distance around the drum (circumference) then divide that number by 3.14.
 

          A
           
           
D          
           
           
           
    B      
           

 

          

 Cable Diameter        Value of "K"                        Cable Diameter      Value of "K"

1/4"

3.29

  

1 & 1/2"

0.107

5/16"

2.21

  

1 & 5/8"

0.0886

3/8"

1.58

  

1 & 3/4"

0.077

7/16"

1.19

  

1 & 7/8"

0.0675

1/2"

0.925

  

2"

0.0597

9/16"

0.741

  

2 & 1/8"

0.0532

5/8"

0.607

  

2 & 1/4"

0.0476

3/4"

0.428

  

2 & 3/8"

0.0421

7/8"

0.308

  

2 & 1/2"

0.038

1"

0.239

  

2 & 5/8"

0.0345

1 & 1/8"

0.191

  

2 & 3/4"

0.0314

1 & 1/4"

0.152

  

2 & 7/8"

0.0287

1 & 3/8"

0.127

  

3"

0.0264