243+ iOS apps curated and reviewed
Every iPhone needs a few good rule of three calculator apps. We benchmark 243+ of them on App Store rating, freshness, and pricing, then surface the standouts so you don't have to scroll the App Store yourself.
| # | App | Price | Rating | Ads | In-App Purchases | Updated |
|---|---|---|---|---|---|---|
| 1 |  | Free | 2.3★ (4) | No | Yes | May 2026 |
| 2 |  | Free | — | No | Yes | May 2026 |
| 3 |  | Free | 5.0★ (2) | No | No | May 2026 |
| 4 |  | Free | — | No | Yes | Jul 2026 |
| 5 |  | Free | 5.0★ (3) | No | No | Jul 2026 |
| 6 |  | Free | 4.8★ (20) | No | Yes | May 2026 |
| 7 |  | Free | 4.9★ (404K) | Yes | No | Jul 2026 |
| 8 |  | Free | 4.7★ (60K) | No | No | Jul 2026 |
This utility app helps you solve problems involving ratios and proportions. It calculates an unknown number based on the relationship between two other known numbers.
This utility app helps users perform quick calculations for everyday scenarios like fuel consumption, currency conversion, and grocery shopping. It features a simple interface with options for result display customization and supports dark/light modes.
This utility app simplifies calculations using the rule of three. It offers a straightforward interface for solving proportion problems, making it easy to find unknown values. The app is completely free and ad-free.
This app simplifies product multiplication calculations with a quick ratio calculator. Easily copy results to your clipboard or save them for future reference in your history with a premium account.
This utility app offers a clean and intuitive interface for performing calculations. It prioritizes a user-friendly design with large buttons and a clear display for quick and efficient use.
This app offers both basic and scientific calculation modes with over 30 scientific operations. It allows for customization of the app's appearance and includes features for note-taking, drawing, and viewing calculation history. It supports high accuracy calculations and nested parentheses.
Easily solve proportion problems with a simple and intuitive interface. This app uses the cross product method for quick and accurate calculations across various fields like finance and science. It's available offline and free to use.
This app helps you quickly solve for an unknown value in a proportion. Simply input three known numbers, and it will calculate the fourth, making ratio and proportion calculations effortless.
This multi-function calculator offers basic to advanced scientific and algebraic computations. It includes features like handwriting recognition, equation solvers, and 2D graphing, making it suitable for students and professionals. In-app purchases unlock advanced capabilities.
This utility app simplifies calculations involving proportional quantities, commonly known as the rule of three or cross-multiplication. It helps solve everyday problems like adjusting recipe ingredients or calculating fuel consumption quickly and easily.
Instantly calculate proportions and simplify everyday math problems with this app. It features a recipe scaler to adjust ingredients and a rule of three calculator for quick, accurate solutions. An intuitive Q&A tool also helps solve homework-style questions.
This utility app offers a straightforward calculation experience with a vast selection of over 80 customizable themes. Personalize your calculator's appearance to suit your style while performing everyday math tasks.
A straightforward and reliable calculator application designed for iPad and iOS 9. It offers a standard calculation experience with a charming piano sound effect and is optimized for high-resolution screens.
This app offers a straightforward calculation experience, focusing on essential functions without unnecessary complexity. It includes basic arithmetic, percentage calculations, and advanced functions like square root. Users can customize the appearance with multiple color schemes and utilize features like result copying and split-screen multitasking on iPad.
This app offers a free basic and scientific calculator with an intuitive interface. It supports fractions, percentages, and advanced editing. Optional upgrades provide specialized calculators for fractions with units, polynomial and linear equation solving, graphing, and geometric shapes.
A straightforward and user-friendly calculator designed for iPhone and iPad. It offers standard calculation logic, basic math operations, and a history display for convenience. Optimized for a simple and efficient user experience.
A straightforward calculator app designed for simplicity, offering basic arithmetic operations and percentage calculations. It allows users to record and recall past results, customize colors, and enable touch sounds for a personalized experience.
A free, classic calculator app with large, easy-to-press buttons and customizable skins. It supports basic arithmetic, memory functions, and can handle very large numbers without using scientific notation. Multitasking is also supported on compatible devices.