Calculate your vehicle's top speed for each gear using transmission ratios, differential gear ratio, and rev limit. Optimize your car's gear ratio for track performance or drag racing, choosing between kmh and mph units.



116+ iOS apps curated and reviewed
If you already know Racing Diffs, this is the deeper bench. 116+ gear ratio apps for iPhone, all reviewed and ranked by user rating, recency, and download trend as of July 2026.
| # | App | Price | Rating | Ads | In-App Purchases | Updated | |
|---|---|---|---|---|---|---|---|
| 1 | Free | 2.5★ (2) | No | No | May 2026 | ||
| 2 | Free | 3.7★ (3) | No | No | May 2026 | ||
| 3 | Free | 3.3★ (3) | No | No | May 2026 | ||
| 4 | Free | 4.4★ (24) | No | Yes | Sep 2026 | ||
| 5 | Free | 3.0★ (1) | No | Yes | May 2026 | ||
| 6 | $0.99 | 3.8★ (120) | No | No | Aug 2026 | ||
| 7 | Free | 5.0★ (1) | No | Yes | May 2026 | ||
| 8 | Free | 1.0★ (1) | No | Yes | Aug 2026 |



Calculate your vehicle's top speed for each gear using transmission ratios, differential gear ratio, and rev limit. Optimize your car's gear ratio for track performance or drag racing, choosing between kmh and mph units.




Calculate essential dimensions for spur gears and pinions using diametral pitch or module. This tool provides outside diameter, center distance, and ratio for specific gear types.




This application simplifies driveline setup and predicts performance changes from gear ratios and tire size. It offers tools to calculate vehicle speed and RPM variables, aiding in rig planning and performance expectation.