Instructions: Input axle ratio, transmission ratio, tire diameter, and vehicle speed for up to three different drivetrain combinations to view engine speed (RPM) under those conditions.
*For automatic transmissions, calculations will only be accurate under the assumption that the torque converter is locked.
**Advertised tire sizes are nominal values. For best results, measure actual tire height to nearest 1/4 inch.
Common Transmission Ratio Chart
| Transmission | 1st (:1) |
2nd (:1) |
3rd (:1) |
4th (:1) |
5th (:1) |
6th (:1) |
R (:1) |
| GM TH350 | 2.52 | 1.52 | 1.00 | - | - | - | 2.07 |
| GM TH400 | 2.48 | 1.48 | 1.00 | - | - | - | 2.07 |
| Ford C4 | 2.46 | 1.46 | 1.00 | - | - | - | 2.18 |
| Ford C6 | 2.46 | 1.46 | 1.00 | - | - | - | 2.18 |
| Chrysler 727 | 2.45 | 1.45 | 1.00 | - | - | - | 2.20 |
| Chrysler 47RE/47RH | 2.45 | 1.45 | 1.00 | 0.69 | - | - | 2.21 |
| Chrysler 48RE | 2.45 | 1.45 | 1.00 | 0.69 | - | - | 2.21 |
| Ford AOD/AODE | 2.40 | 1.47 | 1.00 | 0.67 | - | - | 2.00 |
| Ford E4OD | 2.71 | 1.54 | 1.00 | 0.71 | - | - | 2.18 |
| GM 4L60E | 3.06 | 1.63 | 1.00 | 0.70 | - | - | 2.29 |
| GM 4L80E | 2.48 | 1.48 | 1.00 | 0.75 | - | - | 2.07 |
| Ford 4R100 | 2.71 | 1.54 | 1.00 | 0.71 | - | - | 2.18 |
| Chrysler 68RFE | 3.23 | 1.84 | 1.41 | 1.00 | 0.82 | 0.63 | 4.44 |
| Ford 5R110W (TorqShift 5) | 3.11 | 2.20 | 1.54 | 1.00 | 0.71 | - | 2.88 |
| Ford 6R140 (TorqShift 6) | 3.97 | 2.32 | 1.52 | 1.15 | 0.86 | 0.67 | 3.28 |
| Allison 1000 (5 spd) | 3.09 | 1.81 | 1.41 | 1.00 | 0.71 | - | 4.48 |
| Allison 1000 (6 spd) | 3.09 | 1.81 | 1.41 | 1.00 | 0.71 | 0.61 | 4.48 |
| Aisin AS69RC | 3.75 | 2.00 | 1.34 | 1.00 | 0.77 | 0.63 | 3.54 |
| Muncie SM465 | 6.55 | 3.58 | 1.57 | 1.00 | - | - | 6.09 |
| Borg Warner T-19 | 4.02 | 2.41 | 1.41 | 1.00 | - | - | 6.96 |
| GETRAG G360 | 5.53 | 3.02 | 1.60 | 1.00 | 0.77 | - | 5.03 |
| New Venture NV4500 (Dodge) | 5.61 | 3.04 | 1.67 | 1.00 | 0.75 | - | 5.61 |
| New Venture NV4500 (late GM) | 5.61 | 3.04 | 1.67 | 1.00 | 0.75 | - | 5.61 |
| New Venture NV4500 (early GM) | 6.34 | 3.44 | 1.71 | 1.00 | 0.73 | - | 6.34 |
| New Venture NV5600 | 5.63 | 3.38 | 2.04 | 1.39 | 1.00 | 0.73 | 5.63 |
| ZF S5-42, S5-47 (wide ratio) | 5.72 | 2.94 | 1.61 | 1.00 | 0.76 | - | 5.24 |
| ZF S6-650, S6-750 | 5.79 | 3.30 | 2.10 | 1.31 | 1.00 | 0.72 | 5.23 |
| Mercedes G56 (05 - 07) | 6.29 | 3.48 | 2.10 | 1.38 | 1.00 | 0.79 | 6.29 |
| Mercedes G56 (07.5+) | 5.94 | 3.28 | 1.98 | 1.31 | 1.00 | 0.74 | 5.42 |
For more information on transmissions found in diesel applications, see transmission tech @ Diesel Hub.