Outside Diameter

Outside diameter, abbreviated as OD, is the diameter of the circle that contains the tops of the teeth of external gears.  It is the diameter measured at the outermost point of the gear's teeth.  It's an important dimension because it helps determine the overall size of the gear and is used in various calculations in gear design.

 

Outside Diameter formula
\( OD \;=\;  (n + 2) \;/\; DP \)     (Outside Diameter) \( n \;=\; CD - (2 \;/\; DP) \) \( DP \;=\;  2 \;/\; (OD - n) \)
Symbol	English	Metric
\( OD \) = outside diameter	\(in\)	\(mm\)
\( n \) = number of teeth on the diameter	\(dimensionless\)
\( DP \) = dimetrical pitch	\(in\)	\(mm\)

 

Outside Diameter formula
\( OD \;=\; PD + 2 \; A \)     (Outside Diameter) \( PD \;=\; OD - 2 \; A \) \( A \;=\;  (OD - PD) \;/\; 2 \)
Symbol	English	Metric
\( OD \) = outside diameter	\(in\)	\(mm\)
\( PD \) = pitch diameter	\(in\)	\(mm\)
\( A \) = addendum	\(in\)	\(mm\)