Ratio Calc!
Gearing for your R/C car
$2.99 · In‑App Purchases · Designed for iPad
Ratio Calc is a quick and easy tool for radio control car racers to use trackside. Knowing your final drive ratio (FDR) is very useful for comparison with other racers to determine if your car is geared correctly.
It lets you quickly select your car by filtering on manufacturer and model. Select your pinion and spur size and the FDR is displayed. Tyre diameter can also be entered to calculate your rollout.
Ratio and roll out charts are also available which plot pinion and spur gear combinations to create very handy reference tables.
- Save your favourite cars for quick access
- Select measurement units (imperial/metric)
- Select your preferred gear pitch, alternative ratios in other pitches will be shown
- Over 2000 cars/variants in the database which is updated regularly
-Car search now works by manufacturer name as well
-Fixed some manufacturer logo display issues
-Improved the database update process
-Some updated manufacturer logos
-Fixed an issue with Zen Racing no longer showing
The developer, David Mills, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- David Mills
- Size
- 48.6 MB
- Category
- Sports
- Compatibility
Requires iOS 16.6 or later.
- iPhone
Requires iOS 16.6 or later. - iPad
Requires iPadOS 16.6 or later. - Mac
Requires macOS 13.5 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- Languages
English and 3 more
- English, German, Italian, Spanish
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Nice Tip $0.99
- Generous Tip $2.99
- Mega Tip $4.99
- Insane Tip $9.99
- Copyright
- © 2011-2025 David Mills