# Gear Ratio > Utility app for calculating vehicle gear ratios, driveline ratios, and speeds. (iPhone/iPad app by Robert Sayman.) - Source: https://appshunter.io/ios/app/gear-ratio/id294174897 (this page in markdown: same URL + `.md`) - Developer: [Robert Sayman](https://appshunter.io/developer/289256331) - Category: Utilities, Reference - Price: $1.99 - Rating: 3.00/5 from 1 App Store ratings · 3 written reviews indexed - Age rating: 4+ - Requires: iOS 4.0 · 0 MB - Languages: American English - Released: 2008-10-21 - Data updated: 2026-06-05 - Monetization: paid - User reviews in markdown: https://appshunter.io/ios/app/gear-ratio/id294174897/reviews.md ## What is Gear Ratio? Gear Ratio is a simple utility that calculates gear ratio, driveline ratio, and vehicle speed in both US and Metric units. Enter the input and output gear teeth, the axle ratio, the tire size , and engine speed. Gear Ratio calculates the gear ratio, the driveline ratio, and the vehicle speed from the inputs. - Axle Ratio: To calculate for a kart, bicycle, or other vehicles without a differential, just leave the axle ratio input set to 1.0 - Tire Size can be input in three different ways; Circumference, Revolutions/Mile (or KM), and Rolling Radius. If you race a kart, or other vehicle where changing drive ratios is common, this program is exactly what you need handy and in your pocket at the track. Gear Ratio will correctly calculate for any kind of vehicle: karts, race cars, bicycles, trucks, or anything else. Gear Ratio has six independent pages so you can enter and check several different scenarios. Since the history is also saved, each pages last value can be reviewed for quick reference. If you want to save the data on your computer or send it to someone, just click on the "Send" button to email the calculation results. Gear Ratio is designed to work as easily as possible. The calculation is triggered automatically when you enter a value in each of the input fields. ## Key features - Gear ratio calculation - Driveline ratio calculation - Vehicle speed calculation - US and Metric units - Multiple tire size inputs - Save and email results - Independent calculation pages ## Recent user reviews (3 of 3) All indexed reviews: https://appshunter.io/ios/app/gear-ratio/id294174897/reviews.md ### 1/5 — Mr *2010-09-12* On a simple equation The mph calculates to 153.2 mph , then if you select metric it reads only 9.9 kph yeah right ! ### 2/5 — Good idea but needs work *2010-07-21, version 0* When the app is launched it starts with the iPad GUI and immediately malfunctions. It displays numbers incorrectly and never shows the results of it's calculations ### 5/5 — Great Application, Especially For Us Racers!! *2010-05-11, version 0* This is another great application for all the racers out there, probably the non-racer too if you are simply trying to determine speed etc., using your tire diameter, gear ratio and RPM. While my onboard computer does this on track, I can use this to determine these speeds ahead of time by estimating average RPM's for the track I am running and so on. This helps make that last minute gear or tire change as well to try and gain that edge over the competition. This along with the developers other application "Cross Weight" means I am one step closer to leaving my laptop at home on practice / race days and only needing to take my iPhone / Touch to the track (which I do anyway). Great application, I hope the developer keeps 'em coming for us racers! ## Frequently asked questions about Gear Ratio ### What is Gear Ratio used for? Gear Ratio is a utility app designed to calculate gear ratio, driveline ratio, and vehicle speed. It's useful for various vehicles like karts, race cars, bicycles, and trucks. ### Does Gear Ratio support different units? Yes, Gear Ratio supports both US and Metric units for calculations, making it versatile for a wide range of users. ### How does Gear Ratio handle tire size input? You can input tire size in three different ways: by circumference, revolutions per mile (or kilometer), or rolling radius. ### Can I save my calculations with Gear Ratio? Yes, the app saves the last value for each of its six independent pages, allowing for quick review and reference. You can also email your calculation results. ### What is the price of Gear Ratio? Gear Ratio is a paid application, priced at $1.99. This one-time purchase grants you access to all its features. ### How often is Gear Ratio updated? The latest version of Gear Ratio is 2.4, which was released on October 21, 2011. The app has not seen updates since then. ### What devices is Gear Ratio compatible with? Gear Ratio is designed to work on iPhones, iPads, and iPods. It is suitable for users within the Apple ecosystem. ### What is the age rating for Gear Ratio? Gear Ratio has an age rating of 4+, indicating it is suitable for children and adults alike, with no mature content. ## Version history (last 5 releases) ### 2.4 — 2011-10-21 Improved iOS5 compatibility ### 2.3 — 2010-12-18 - Improved compatibility with iOS 4.2 ### 2.2 — 2010-08-17 - Fixed decimal point so it shows properly on the keypad ### 2.1 — 2010-08-06 - Corrected interface bugs in 4.0 and higher ### 2.0 — 2010-04-22 - New iPad Interface - Added Transfer Case Ratio - Added Notes Field - Now has 10 Screens (was 6) ## More apps by Robert Sayman - [Base Converter](https://appshunter.io/ios/app/base-converter/id289256328) - [Cross Weight](https://appshunter.io/ios/app/cross-weight/id290618962) - [Clothes Size](https://appshunter.io/ios/app/clothes-size/id296096468) - [Gift Track - Planner, Reminder, and List Maker](https://appshunter.io/ios/app/gift-track-planner-reminder-and-list-maker/id314810819) All apps by Robert Sayman: https://appshunter.io/developer/289256331 ## Related topics [ratio gear](https://appshunter.io/ios/topics/ratio-gear) --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-05.*