About Transmission Gear Ratio & Speed Calculator
Analyze transmission and differential gearing. Computes effective drive ratios, top speed per gear at redline RPM, and shift RPM drops between gears for optimal track, quarter-mile drag, and highway cruising performance.
Key Capabilities & Features
- Multi-gear transmission analysis for 5, 6, 7, and 8-speed manual and automatic transmissions
- Calculates effective drive ratios combined with differential final drive
- Computes theoretical top speed in each gear at engine redline in both mph and km/h
- Calculates exact shift RPM drops to identify whether engine stays in peak power band
How to Use Transmission Gear Ratio & Speed Calculator
1
Input Gear Ratios
Enter each transmission gear ratio (1st through 6th/8th).
2
Set Final Drive & Tire Size
Specify rear axle ratio and overall tire diameter in inches.
3
Set Engine Redline
Input maximum RPM limit of your engine.
4
Inspect Gearing Table
Review top speeds per gear and RPM drops upon upshifting.
Privacy & In-Browser Execution Guarantee
100% client-side calculation. Your data never leaves your browser.
Frequently Asked Questions
How is vehicle speed in gear calculated?
Speed (mph) = (Engine RPM × Tire Diameter in inches) / (Gear Ratio × Final Drive × 336).
What is a final drive ratio?
The final drive (differential) ratio provides the final mechanical gear reduction between the transmission output shaft and the driven wheels.
Related Tools in this Suite
Engine RPM & Speed Calculator
Calculate engine RPM from vehicle speed, gear ratio, final drive, and tire size
Engine Displacement Calculator
Calculate engine displacement in CC, Liters, and CID from bore, stroke, and cylinder count
Tire Size Comparison & Speedometer Error
Compare tire diameters, section widths, sidewall heights, and speedometer calibration