You can find a swing weight scale in most golf shop. But you can also measure it yourself by using weight scale and measuring tape .By doing this , you can try & calculate it by trying this method.
Before this you should know the calculation formula :
Take an example of a driver
length 45.75inch , weight 307.8g (= 10.86ounce)
balance point from grip end is 83.5cm
As mentioned before at moment ,
(distance from action point and center of rotation ) x (force)
action point : 83.5cm = 32.87inch
center of rotation : 14inch from grip end
32.87-14 = 18.87 inch
then multiple by force ( = club weight)
18.87x10.86 = 204.9 inch.ounce
Please see the table
C8 = 210 inch.ounce
So 204.9 is very near to C5.
And mesure it by swing weight scale, then get the same result.
That is ok.
The balance is calculate from the value of the moment (inch ounce) when expressing it in
A0 → 0 , B0 → 10 , C0 → 20 , D0 → 30
⇒ balance = (moment -161)x4/7
= 25.08 so C5.08