Crawl Ratio Calculator

Enter your transmission, transfer case, and axle gear ratios into the left side of the form below and press the calculate button to find your final crawl ratio.

Transmission Ratio: : 1
Transfer Case Ratio: : 1
Axle Gear Ratio: : 1
Final Crawl Ratio:
: 1



Final Crawl Ratio: 50:1 100:1 150:1 200:1
35" tires at 1,500 rpm 3.2 mph 1.6 mph 1.0 mph 0.7 mph
37" tires at 1,500 rpm 3.5 mph 1.7 mph 1.1 mph 0.8 mph
42" tires at 1,500 rpm 3.9 mph 1.9 mph 1.3 mph 1.0 mph

To calculate for a different RPM, use our Engine RPM calculator.



NEW! - Need help with this calculator? Check out the new comments section below!


Axle Parts


Crawl Ratio Calculation Basics

The crawl ratio is the number of rotations your engine makes before your tires make one full turn. The ratio is calculated by multiplying your transmission, transfer case, and ring and pinion gear ratios. Off-road drivers and rock crawlers build their vehicles with low (numerically high) crawl ratios because not only does that increase torque at the wheels, it allows for better throttle response for low speed, technical driving.

[ Transmission Ratio x Transfer Case Ratio x Axle Ratio ] = [ 2.48 x 2.72 x 3.73 ] = [ 25.16 : 1 ]



Popular Transmission and Transfer Case Ratios

Transmission1st Gear2nd Gear3rd Gear4th Gear

Chrysler TF-727 2.45:1 1.45:1 1.00:1
Chrysler TF-904 2.45:1 1.45:1 1.00:1
Chrysler A-500 / 42RH 2.74:1 1.54:1 1.00:1 0.69:1
Chrysler A-518 / 618 / 47RH 2.45:1 1.45:1 1.00:1 0.69:1

Ford C4 2.46:1 1.46:1 1.00:1
Ford C6 2.46:1 1.46:1 1.00:1
Ford AOD 2.40:1 1.47:1 1.00:1 0.67:1
Ford AODE-W / 4R70W 2.84:1 1.55:1 1.00:1 0.70:1

GM Powerglide (Small Block) 1.76:1 1.00:1
GM Powerglide (Big Block) 1.82:1 1.00:1
GM 200-4R 2.78:1 1.57:1 1.00:1 0.67:1
GM TH350 / Turbo 350 2.52:1 1.52:1 1.00:1
GM TH400 / Turbo 400 2.48:1 1.48:1 1.00:1
GM 700R4 / 4L60E 3.06:1 1.63:1 1.00:1 0.70:1
GM 4L80E / 4L85E 2.48:1 1.48:1 1.00:1 0.75:1

Transfer CaseHigh RangeLow Range

Borg Warner 1339 1.00:1 2.57:1
Borg Warner 1350 1.00:1 2.48:1
Borg Warner 1356 1.00:1 2.72:1

Dana / Spicer 18 1.00:1 1.97 / 2.46:1
Dana 20 1.00:1 2.34 / 2.46:1
Dana 300 1.00:1 2.62:1

NP 203 1.00:1 1.96:1
NP 205 1.00:1 1.96:1
NP 208 / 209 1.00:1 2.69:1
NP 228 / 229 1.00:1 2.69:1
NP 231 / NP231HD 1.00:1 2.72:1
NP 241 / NP241HD 1.00:1 2.72:1
NP 261 / 263 1.00:1 2.76:1
NP 271 / 273 1.00:1 2.72:1

To find your axle gear ratio, please see our Ring and Pinion Gear Ratio Calculator







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Street Legal Laws

To find the street legal laws for your state including maximum suspension lift heights and tire size rules visit LiftLaws.com