# Base Circle

on . Posted in Gear

Base circle, abbreviated as BC, is a circle from where involute portion of tooth profile will be produced.

## Base Circle formula

$$\large{ BC = PD \; cos\; PA }$$
Symbol English Metric
$$\large{ BC }$$ = base circle $$\large{in}$$ $$\large{mm}$$
$$\large{ PD }$$ = pitch diameter $$\large{in}$$ $$\large{mm}$$
$$\large{ PA }$$ = pressure angle $$\large{deg}$$ $$\large{rad}$$

Tags: Gear Equations