Gear-by-Gear Speed Calculator
See the top speed in each gear. Use the calculator below. Results update as you type.
How the Gear-by-Gear Speed Calculator Works
This calculator works by running the speed-at-RPM formula once for each transmission gear at a chosen engine RPM. It shows the theoretical top speed in every gear.
- Enter the tire diameter, for example 31 in.
- Enter the final drive ratio, for example 3.73.
- Enter each gear ratio and the engine RPM, for example 6,000.
- Read the speed in each gear: 35.6 mph in 1st, up to 215.0 mph in 6th (theoretical).
The Formula
The formula is Speed_gear = (RPM × Diameter) ÷ (Axle × Gear_ratio × 336.13), applied to each gear.
Speed_i (mph) = (RPM × D) ÷ (Axle × G_i × 336.13) Speed_i (km/h) = Speed_i (mph) × 1.609344Worked example for 3rd gear at 1.52: (6,000 × 31) ÷ (3.73 × 1.52 × 336.13) = 97.6 mph (157 km/h).
Conversion Table
The conversion table shows theoretical speed at 6,000 RPM in 6 gears for 31 in and 33 in tires, with a 3.73 axle. The 33 in tire adds 6.5% to every gear's speed.
Top-gear figures above 150 mph are theoretical. Aerodynamic drag and engine output cap real speed well below them.
| Gear | Ratio | 31 in (mph) | 31 in (km/h) | 33 in (mph) | 33 in (km/h) |
|---|---|---|---|---|---|
| 1st | 4.17 | 35.6 | 57 | 37.9 | 61 |
| 2nd | 2.34 | 63.4 | 102 | 67.5 | 109 |
| 3rd | 1.52 | 97.6 | 157 | 103.9 | 167 |
| 4th | 1.14 | 130.1 | 209 | 138.5 | 223 |
| 5th | 0.87 | 170.5 | 274 | 181.5 | 292 |
| 6th | 0.69 | 215.0 | 346 | 228.9 | 368 |
Gear ratios shown are an example 6-speed set; enter your transmission's published ratios in the calculator.
What Is the Gear-by-Gear Speed Calculator?
The Gear-by-Gear Speed Calculator is a tool that shows how fast a vehicle can go in each gear at a set engine speed. Racers use it to plan shift points; off-road drivers use it to see crawl speed in 1st gear.
A tire change shifts every gear's speed by the same percentage. The table makes that shift visible gear by gear.
Common Uses
This calculator has 4 uses: shift planning, drag racing, crawl planning and gearbox comparison.
- Plan shift points: Know road speed at redline in each gear.
- Set up drag cars: Match gear speeds to track length.
- Plan crawl speeds: See 1st-gear speed at idle.
- Compare gearboxes: Test 2 transmissions on one tire.