Apps in this category may contain mild or occasional cartoon, fantasy or real-life violence, as well as occasional or mild adult, sexually suggestive or horrifying content and may not be suitable for children under 9 years of age.

12+

Apps in this category may contain occasional mild indecent language, frequent or intense cartoon or real-life violence, minor or occasional adult or sexually suggestive material, and simulated gambling, and may be for children under 12 years of age.

17+

You must be at least 17 years old to access this App.

Apps in this category may contain frequent and intense offensive language; Frequent and intense cartoon, fantasy or realistic violence: frequent and intense adult, scary and sexually suggestive subjects: as well as sexual content, nudity, tobacco, alcohol and drugs, may not be suitable for children under 17 years of age.

Ratio Calc! Screenshots

iPad

iPhone

About Ratio Calc!

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

What's New in the Latest Version 6.6

Last updated on Feb 23, 2019

Old Versions

-Support for the latest devices and iOS
-Improved the database update process to show more details
-Removed the text erasing buttons on the text fields when editing notes
-Moved the gear and diameter pickers up so that the results can be seen whilst changing the settings
-Updated database and manufacturers
-Various other little tweaks and improvements

Enjoy your R/C racing!

Version History

6.6

Feb 23, 2019

6.5

Jan 23, 2018

We've added a tip jar - the app has been kept up to date since 2011 and we've never charged for an update. Any tip will unlock the ability to change the app's colour scheme and app icon - we've even included some retro icons that may be familiar to long time users.

Also in this version:
-Improved watch app reliability
-Transponder input form improvements
-Other boring little fixes and optimisations

6.4

Jan 8, 2018

-iPhone X support
-Improved Apple Watch app (watchOS 2+ required)
-Now you can save motor and timing details for your saved cars
-Improved displays when using larger display fonts

6.3.1

Jan 26, 2017

- Change of support email address

Enjoy your racing!

6.3

Nov 11, 2016

-You can now update the car database more easily
-iOS10 compatibility
-Latest car database included

6.2

May 14, 2016

-Improved car database updating - simply pull to refresh on the manufacturers screen
-Quickly copy your transponder number into the clipboard
-Fixed an issue with the ruler displaying incorrectly
-Improved iPad Pro support

6.1

Nov 3, 2015

- Transponder store improvements - you can now save more than 3 transponder numbers - thanks to Jason H for the suggestion.
****Note:**** Please ensure you visit the transponder store part of the app to migrate your existing transponder numbers over to the new version. Until this is done they will not show in the Today widget or on the Apple Watch Glance.
- iPad multitasking support for iO9
- Revised app layouts - faster navigation using tabs
- Several other tweaks and improvements

6.0.1

Oct 6, 2015

-Database update URL has now changed. This version is required to continue receiving car database updates.
-Fixed a bug which hid the car notes under the keyboard if the note was more than a few lines long. Thanks Michael T for reporting this.

6.0

May 28, 2015

Introducing Ratio Calc! for Apple Watch - view your cars ratio/rollout with ease.

Now you can store your transponder numbers so that they're available quickly when booking in - view them either on the Apple Watch or on the Today screen (iOS8 required).

If you love using Ratio Calc! please leave a review - it's greatly appreciated. Many thanks.

5.10

Jan 26, 2015

-Updated for iOS8, iPhone 6, iPhone 6+
-Latest car database
-iOS7 is now a minimum requirement
-Bug fixes

5.03

Jun 5, 2014

-Quick access chart buttons for saved cars now display correct pinion/spur info

5.02

Apr 2, 2014

More iOS7 bugfixes - sorry :-(

5.01

Mar 28, 2014

-Bug fixes (iOS 7.x)
-Latest database
-Performance improvements

5.0

Feb 19, 2014

-New look and layout
-Requires iOS6 and above
-84 DP, Mod 0.4, Mod 0.6 pitch support

4.80

Oct 28, 2013

*Bug fixes
*latest database and logos

4.70

Mar 25, 2013

-iPad support!
-Latest database

4.60

Dec 13, 2012

-Mod 1.0 support
-Mod 0.8 support
-Latest database

4.50

Sep 21, 2012

*** requires at least iOS 4.3 ***
- iPhone 5 support
- Latest car database
- Updated logos

4.40

Jun 13, 2012

-Additional language support
-Latest car database

4.30

Mar 7, 2012

- Maximum pinion size is now 100T

- Latest car database

- Updated manufacturer logos

4.20

Jan 11, 2012

- Saved cars now remember their gear pitch setting to make it easier for racers that use different DP with different cars

- Gear pitch (DP) can now be changed whilst in the calculator, not just in settings

- The saved cars list can now be re-arranged

- Updated car database and logos

4.10

Nov 28, 2011

- Smaller changes in tyre diameter now possible
- Some small user interface changes
- Latest car database
- Updated manufacturer logos

4.01

Jul 22, 2011

- Save notes against your cars

- Switch gear pitch easily using the suggested equivalent sizes

- Maximum tyre diameter increased

- Updated car database

- Updated manufacturer logos

- Fixed small bug that sometimes erased saved track notes

4.0

Jul 18, 2011

- Save notes against your cars

- Switch gear pitch easily using the suggested equivalent sizes

- Maximum tyre diameter increased

- Updated car database

- Updated manufacturer logos

3.41

May 12, 2011

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