How do I determine gear ratio? 1

[JOHNMCC]

How do I determine the gear ratio of an automotive differential?
I have a trashed rear end, & have it apart so I will be able to count the teeth.
I know this has to be an easy one, but I'm still getting over the "sticker shock" of the cost of replacing it.
Thank's in advance,
John

 

[butelja]

Number of ring gear teeth divided by number of pinion teeth will give you the gear ratio.

 

[chadtoolio]

JOHNMCC,

Alot of times there is a number stamped into the ring gear (100/25)=4.00 to 1, but Butelja is correct, count the teeth