Ratio Calc!

Ratio CalcDownload on the App Store

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 class, 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
  • Save notes and track name against your favourite cars
  • Send ratio charts via email
  • Suggest new cars from within the app
  • Download new cars from within the app at the click of a button
  • Select measurement units (imperial/metric) via Settings
  • Select your preferred gear pitch, alternative ratios in other pitches will be shown
  • Currently over 1300 cars/variants in the database. View the full list here
by mnkyrcng Very Useful

This app is about as good as it gets. Very functional, without any silliness or distractions. I use it every time I race or tune.

by Cancun Tom App for real racers

I wouldn't leave home without it. Gone are all my charts, calipers and notes. Good job guys!

by Nnyeah Excellent App

Great app for RC gear ratios. A must have.