# Ratio Calc!

> Gearing for your R/C car

Canonical page: [https://chrome-stats.com/d/id436311293](https://chrome-stats.com/d/id436311293)

## Overview

- **ID:** `id436311293`
- **Platform:** Apple
- **Type:** Apple app
- **Status:** Available
- **Publisher:** David Mills
- **Category:** Sports
- **Rating:** 4.50 / 5 (25 ratings)
- **Version:** 7.5.1
- **Last updated:** 2025-11-11
- **First published:** 2011-05-12
- **Size:** 46 MB
- **Data as of:** 2026-09-18
- **Store listing:** [Apple App Store](https://apps.apple.com/us/app/ratio-calc/id436311293)
- **Website:** [https://www.sllim-code.com](https://www.sllim-code.com/)
- **Privacy policy:** [https://www.sllim-code.com/privacy-policy/](https://www.sllim-code.com/privacy-policy/)

## Description

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

## Rankings

- #229,752 — Overall

## Review summary

Ratio Calc! is highly praised for its large car library, fast gear ratio and rollout calculations, and easy-to-use interface. Reviewers value storing multiple cars, comparing final drive and rollouts, and its strong on-track usefulness. The main drawbacks cited are the desire for more frequent updates/new kits and the lack of per-car gear pitch settings. Overall, it’s regarded as a must-have tool for RC racers with room for feature enhancements.

### Pros

- Large car library with easy addition of new cars
- Fast, accurate gear ratio and rollout calculations
- Easy to use with a clean, intuitive UI
- Stores multiple cars and allows quick comparisons of final drive ratios and rollouts
- On-track usefulness and updates add new cars quickly

### Cons

- Requests for more frequent updates and inclusion of new kits
- Lacks per-car gear pitch settings; gear pitch cannot be set for each car

## Similar extensions and apps

- [RC Pit Calc Pro](https://chrome-stats.com/d/id1562268871) — 4.40 / 5
- [RC-GEAR](https://chrome-stats.com/d/id1618154073) — 4.30 / 5
- [RC Rollout Calculator](https://chrome-stats.com/d/id6760838974)
- [R2 GearCalc](https://chrome-stats.com/d/id6797484645)
- [Gear Ratio](https://chrome-stats.com/d/id294174897) — 3.00 / 5
- [RC-DD ROLLOUT](https://chrome-stats.com/d/id1630032562) — 5.00 / 5
- [Kart Gear Ratios](https://chrome-stats.com/d/id6468892566)
- [Racing Diffs - Gear ratio](https://chrome-stats.com/d/id1554897307) — 2.50 / 5
- [Gear Formula: Calc & Simulator](https://chrome-stats.com/d/id6786232651)
- [Karting Gearing Ratios](https://chrome-stats.com/d/id6483539357) — 1.00 / 5
- [Slotcar GearCalc](https://chrome-stats.com/d/id6740806046)
- [Gear Ratio Calculator & RPM](https://chrome-stats.com/d/id6771942447)

---

Source: [Chrome-Stats](https://chrome-stats.com/d/id436311293)