Engine RPM Calculator
Enter your axle gear ratio, tire diameter, vehicle speed, and transmission gear ratio in the blue fields and click the calculate button to find your engine RPM.
Engine RPM Calculation Basics
Engine RPM, or the speed at which the engine turns, can be calculated at any speed given the vehicle's tire size, axle ratio, and final transmission gear ratio. This calculation is used to match oversize tires with new ring and pinion gears to obtain the desired engine RPM at highway speed.
Note: 336.13 is used to convert the result to RPM = [63360 inches per mile / (60 minutes per hour x Pi.)]
Popular Transmission Ratios
| Transmission | 1st Gear | 2nd Gear | 3rd Gear | 4th Gear | 5th Gear | 6th Gear |
|---|---|---|---|---|---|---|
| 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 | ||
| Chrysler TorqueFlite 727 | 2.45:1 | 1.45:1 | 1.00:1 | |||
| Chrysler TorqueFlite 904 | 2.45:1 | 1.45:1 | 1.00:1 | |||
| Chrysler TorqueFlite 999 | 2.74:1 | 1.55:1 | 1.00:1 | |||
| 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 | ||
| Ford 4R100 | 2.71:1 | 1.54:1 | 1.00:1 | 0.71:1 | ||
| Ford 5R150 TorqShift | 3.11:1 | 2.22:1 | 1.55:1 | 1.00:1 | 0.71:1 | |
| Ford NP435(E) | 6.68:1 | 3.34:1 | 1.74:1 | 1.00:1 | ||
| Ford NP435(L) | 6.68:1 | 3.34:1 | 1.66:1 | 1.00:1 | ||
| Ford T18 | 6.32:1 | 3.09:1 | 1.69:1 | 1.00:1 | ||
| Ford T19 | 4.02:1 | 2.41:1 | 1.41:1 | 1.00:1 | ||
| Ford T19 (HD) | 6.32:1 | 3.09:1 | 1.68:1 | 1.00:1 | ||
| Ford T19 (Special) | 5.11:1 | 3.03:1 | 1.79:1 | 1.00:1 | ||
| Ford ZF | 5.72:1 | 2.94:1 | 1.61:1 | 1.00:1 | 0.76:1 | |
| 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 / 4L60 | 3.06:1 | 1.63:1 | 1.00:1 | 0.70:1 | ||
| GM 4L60E / 4L65E | 3.06:1 | 1.63:1 | 1.00:1 | 0.69:1 | ||
| GM 4L80 / 4L85 | 2.48:1 | 1.48:1 | 1.00:1 | 0.75:1 | ||
| GM 6L80 | 4.02:1 | 2.36:1 | 1.53:1 | 1.15:1 | 0.85:1 | 0.67:1 |
| GM NP435(A) | 4.56:1 | 2.28:1 | 1.31:1 | 1.00:1 | ||
| GM NP435(D) | 4.90:1 | 2.29:1 | 1.19:1 | 1.00:1 | ||
| GM NV4500 (93-94) | 6.34:1 | 3.44:1 | 1.71:1 | 1.00:1 | 0.73:1 | |
| GM NV4500 (95+) | 5.61:1 | 3.04:1 | 1.67:1 | 1.00:1 | 0.74:1 | |
| GM Powerglide (Small Block) | 1.76:1 | 1.00:1 | ||||
| GM Powerglide (Big Block) | 1.82:1 | 1.00:1 | ||||
| GM SM420 | 7.00:1 | 3.60:1 | 1.70:1 | 1.00:1 | ||
| GM SM465 | 6.55:1 | 3.58:1 | 1.57:1 | 1.00:1 | ||
| Jeep AW4 | 2.80:1 | 1.53:1 | 1.00:1 | 0.75:1 | ||
| Jeep AX15 | 3.92:1 | 2.33:1 | 1.44:1 | 1.00:1 | 0.85:1 | |
| Jeep AX4 | 3.83:1 | 2.33:1 | 1.44:1 | 1.00:1 | ||
| Jeep AX5 | 3.83:1 | 2.33:1 | 1.44:1 | 1.00:1 | 0.79:1 | |
| Jeep BA10/5 | 3.39:1 | 2.33:1 | 1.44:1 | 1.00:1 | 0.79:1 | |
| Jeep NSG370 | 4.46:1 | 2.61:1 | 1.72:1 | 1.25:1 | 1.00:1 | 0.84:1 |
| Jeep NV3550 | 4.01:1 | 2.33:1 | 1.39:1 | 1.00:1 | 0.78:1 | |
| Jeep SR4 (4 Cyl.) | 4.07:1 | 2.39:1 | 1.49:1 | 1.00:1 | ||
| Jeep SR4 (6 Cyl.) | 3.50:1 | 2.21:1 | 1.43:1 | 1.00:1 | ||
| Jeep T176 | 3.52:1 | 2.29:1 | 1.46:1 | 1.00:1 | ||
| Jeep T177 | 3.82:1 | 2.29:1 | 1.46:1 | 1.00:1 | ||
| Jeep T178 | 3.00:1 | 2.08:1 | 1.47:1 | 1.00:1 | ||
| Jeep T18 (72-75) | 6.32:1 | 3.09:1 | 1.69:1 | 1.00:1 | ||
| Jeep T18 (76-79) | 4.02:1 | 2.41:1 | 1.41:1 | 1.00:1 | ||
| Jeep T18 / T19 | 6.32:1 | 3.09:1 | 1.69:1 | 1.00:1 | ||
| Jeep T4 | 4.03:1 | 2.37:1 | 1.50:1 | 1.00:1 | ||
| Jeep T5 | 4.03:1 | 2.37:1 | 1.50:1 | 1.00:1 | ||
| Jeep T98 | 6.40:1 | 3.09:1 | 1.69:1 | 1.00:1 | ||
| Jeep 42RLE | 2.84:1 | 1.57:1 | 1.00:1 | 0.69:1 | ||
| Jeep 45RFE | 3.00:1 | 1.67/1.5:1 | 1.00:1 | 0.75:1 | ||
| Jeep 5-45RFE | 3.00:1 | 1.67/1.5:1 | 1.00:1 | 0.75:1 | 0.67:1 | |
This engine RPM 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.
More Gear and Axle Guides:
Differential Locker Comparison - A detailed comparison of popular differentials and lockers.
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.
