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Ratio Calc! app for iPhone and iPad


4.4 ( 5184 ratings )
Utilities Sports
Developer: David Mills
2.99 USD
Current version: 6.6, last update: 3 years ago
First release : 12 May 2011
App size: 11.56 Mb

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. You can also view your favourite information on Apple Watch.

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

- Save notes and track name against your favourite cars

- Share ratio/rollout charts

- Download new cars from within the app

- Select measurement units (imperial/metric)

- Select your preferred gear pitch, alternative ratios in other pitches will be shown

- Over 1600 cars/variants in the database

Pros and cons of Ratio Calc! app for iPhone and iPad

Ratio Calc! app good for

I use this all the time. Best of the dozens of similar apps Ive tried.
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.

Some bad moments

Very nicely done & easy to use! I was very surprised to find all the Custom Works cars included - even the new Dominator 2. The tables are great for cross referencing ratios rollout! Great App!!!
Works Great. Very Helpful. Works Great at the Race Track!!!! Later HB
this app is great, everything you need it to do. The car database is amazing, its so easy to get more cars added you just email in app and days later they add it. In app updates is another major plus!
Great app. rollout chart is great, my only complaint is i would like to select gear pitch for each car. I use 64p on pan cars and 48 on dirt oval
This app will be a big help at the track. I would say that anyone that races and that has an iPhone should get this app
This app allows quick and easy calculations to be made at the track when you need that little extra to beat the competition.