Enter the chain stay (in), the number of teeth in the front chainring, and the number of teeth in the rear cog into the Chain Length  Calculator. The calculator will evaluate the Chain Length . 

Chain Length  Formula

The following formula is used to calculate the Chain Length . 

CL = 2*C+ (F/4+R/4+1)

  • Where CL is the Chain Length  (inches)
  • C is the chain stay (in) 
  • F is the number of teeth in the front chainring 
  • R is the number of teeth in the rear cog 

How to Calculate Chain Length ?

The following two example problems outline the steps and information needed to calculate the Chain Length .

Example Problem #1

  1. First, determine the chain stay (in).
    • The chain stay (in) is calculated to be : 15.
  2. Next, determine the number of teeth in the front chainring. 
    • The number of teeth in the front chainring is measured to be: 30.
  3. Next, determine the number of teeth in the rear cog. 
    • The number of teeth in the rear cog is found to be: 20.
  4. Finally, calculate the Chain Length  using the formula above: 

CL = 2*C+ (F/4+R/4+1)

The values provided above are inserted into the equation below and computed.

CL = 2*15+ (30/4+20/4+1) = 43.5 (inches)


Example Problem #2

The variables required for this problem are provided below:

chain stay (in) = 16

number of teeth in the front chainring = 50

number of teeth in the rear cog = 40

Test your knowledge using the equation and check your answer with the calculator.CL = 2*C+ (F/4+R/4+1) = (inches)