Mainpring length calculator

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Enter the measurements shown in metric or inches (but not mixed!)
e.g.    D = 50      d = 15         t = 0.45

Barrel diameter (D)        
Arbor diameter (d)          
Spring thickness (t)  

       

Clock Mainspring Length Calculator



This calculates the length using the following formula:

Length = ((((PI x (D/2)2)-(PI x (d/2)2)))/2) /t