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Gear Ratio Calculator

This gear ratio calculator allows you to select your transmission, transfer case, crawl box, axle differential ratio and tire diameter from the 5 columns on the left. The gear information on in the right table is automatically calculated based upon your choices.

I've also included a transmission gear ratio chart below to help you out. It includes the ratios for every gear for side by side comparisions.

If you would like to compare different gear and tire diameter combinations, check out my Gear Ratio versus Tire Diameter page.

Transmission
AX-5
AX-15
NP435
NV3550
NV4500
SM420
SM465
SR-4
T-4
T-5
T-14
T-15
T-18
T-18A
T-86
T-150
T-176
Transfer Case
Atlas II (3.8:1)
Atlas II (4.3:1)
Dana 18 (2.46:1)
Dana 20 (2.02:1)
Dana 300 (std)
Dana 300 (4:1)
NP231 (std)
NP231 (4:1)
Quadra-Trac (2.57:1)
Crawl Box
None
3.5:1
4.0:1
Axle Gear
2.73
3.08
3.31
3.54
3.73
4.10
4.56
4.88
5.13
Tire Size
28
29
30
31
32
33
35
36
38
40
44
Calculation Results
Forward Crawl Ratio: : 1
Reverse Crawl Ratio: : 1
Forward Movement @ RPM: Feet/Sec
Reverse Movement @ RPM: Feet/Sec
Forward Speed @ RPM: MPH

Calculate RPM from MPH using info from above:
Forward MPH requires RPM

 
Jeep Transmission Gear Ratio Information
Transmission 1st 2nd 3rd 4th 5th Rev
AX-53.932.331.451.000.854.74
AX-153.832.331.441.000.794.22
BA 10/53.392.331.441.000.79 
SR-44.072.391.49N/AN/A3.95
T-44.032.371.501.00N/A3.76
T-54.032.371.501.000.863.76
T-184.022.411.411.00N/A4.73
T-18a6.323.091.691.00N/A7.44
T-862.801.691.00N/AN/A3.80
T-986.403.091.691.00N/A 
T-1502.991.751.00N/AN/A3.17
T-1763.522.271.461.00N/A3.52
T-1773.822.291.461.00N/A3.82
T-1783.002.081.471.00N/A3.01
Common Swap Transmission Gear Ratio Information
Transmission 1st 2nd 3rd 4th 5th Rev
SM4207.053.581.711.00N/A7.05
SM4656.553.581.571.00N/A 
TH3502.521.521.00N/AN/A 
TH4002.481.481.00N/AN/A 
700R43.061.621.000.70N/A 

You may want to bookmark this gear ratio calculator and check back as new transmissions, transfer cases, and axle ratios are added.