Off-Road

Crawl Ratio Calculator

Calculate your vehicle's crawl ratio for off-road capability. See how axle ratio, transfer case, and tire size affect rock crawling performance.

Quick Presets

Results

Enter drivetrain specs to calculate crawl ratio

Crawl Ratio Benchmarks

100+ — Competition crawler
70-100 — Serious off-road
50-70 — Capable (Rubicon level)
30-50 — Moderate trails
<30 — Light duty

How to Use

Enter your axle (differential) ratio
Enter transmission 1st gear ratio
Enter transfer case low range ratio
Input your tire diameter

FAQs

What is crawl ratio?

Crawl ratio is the total gear reduction in low range: 1st gear × transfer case low × axle ratio. Higher numbers mean more torque multiplication and slower controlled speeds.

Why do larger tires reduce crawl ratio?

Larger tires travel farther per revolution, effectively reducing the mechanical advantage. A 35" tire vs 31" tire loses about 13% of your effective crawl ratio.

How do I increase crawl ratio?

Options: re-gear to higher axle ratio (most common), install a lower transfer case (Atlas, Marlin), or use smaller tires (least desirable for clearance).

Is higher always better?

Not necessarily. Extremely high ratios (100+) can be jerky and hard to modulate. Most trail rigs do well with 50-70:1. Competition rigs benefit from 100+.

Limitations

Assumes standard drivetrain layout
Does not account for dual transfer cases
Tire deformation under load not factored
Real crawling depends on traction too

Crawl Ratio Calculator

Drivetrain Ratios

Tire Size

Quick Presets

Results

Low Range Speed