Find your Jeep or 4×4’s overall low-range gearing. Enter your transmission, transfer case, and axle ratios to see how many engine revolutions it takes to turn the tires once.
Enter your drivetrain ratios
Use the specifications for your vehicle. Enter ratios as numbers, such as 3.83.
Optional speed estimate
Add tire diameter and engine RPM to estimate theoretical speed in 1st gear and low range.
How is crawl ratio calculated?
Crawl ratio describes the total gear reduction from the engine through the transmission, transfer case, and axle. A numerically higher ratio gives more gear reduction and allows slower wheel speed in low range.
Example: 3.83 × 2.72 × 4.10 = 42.67:1.
This means the engine rotates approximately 42.67 times for one tire revolution, assuming first gear and the selected transfer-case range.
What do the numbers mean?
- Transmission: The numerical ratio of the transmission’s first gear.
- Transfer case: Use the low-range reduction ratio. Use 1.00 when calculating in high range.
- Axle: The ring-and-pinion gear ratio, often stamped on an axle tag or listed in build specifications.
- Tire diameter: Does not change the crawl ratio itself, but it affects ground speed and wheel torque at the contact patch.
Crawl ratio FAQs
What is a good crawl ratio for a Jeep?
It depends on the transmission, tire size, engine characteristics, terrain, and driving style. A stock or lightly modified 4×4 may have a ratio around 20:1–40:1, while dedicated rock-crawling builds often target substantially higher ratios. Treat these as broad examples, not strict pass/fail thresholds.
Does a bigger tire change crawl ratio?
No. The mathematical crawl ratio is determined by the three gear ratios. Larger tires do, however, reduce effective leverage at the ground and increase the distance traveled per tire revolution.
Should I use the transfer case high or low ratio?
Use the low-range ratio to calculate your off-road crawl ratio. Use 1.00 for high range. Make sure you enter the ratio for the transfer case actually installed in your vehicle.
Where can I find my axle gear ratio?
Check the axle identification tag, vehicle build sheet, service records, differential markings, or count the ring-gear and pinion teeth. If the gears have been changed, verify the installed ratio rather than relying only on the factory specification.