You can look up your vin. That will tell you what ratio your Wrangler came with.where can I find the gear ratio, i have a manual 4-door sahara
Or you can count how many times the drive shaft rotates for one rotation of the tires when you roll it forward or backwards.
I used a piece of string and counted how many times it wrapped around the drive shaft when I rolled the Jeep forward one rotation of the tires.
But looking up your vin is probably easier.