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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.



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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




This crawl ratio calculator is ©Copyright Crawlpedia.com - Please provide a link back to this page when copying.
Data is accurate to the best of our knowledge and is offered as-is with no guarantee.



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Gear Ratio Finder - Find the ideal axle gear ratio for your new larger or smaller tires.
Gear Ratio Calculator - Calculate the gear ratio of gears based on their tooth count.
Ring and Pinion Setup Specs - Ring and pinion gear setup specifications for popular axles.
Ring and Pinion Ratio Variations - An explanation of why some ring and pinion gear ratios vary.
Thick Gears and Carrier Breaks - Thick ring and pinion gears and differential carrier breaks explained.