Calculate the correct series resistor needed to safely power light-emitting diodes. Input supply voltage, LED voltage drop, current, and the number of LEDs to find the required resistor value and wattage.


215+ iOS apps curated and reviewed
Every iPhone needs a few good ledd calculator apps. We benchmark 215+ 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 | — | No | No | May 2026 | |
| 2 | $2.99 | 5.0★ (6) | No | No | Jun 2026 | |
| 3 | Free | 4.9★ (33K) | Yes | Yes | Jul 2026 | |
| 4 | Free | 4.7★ (1.7M) | Yes | Yes | Jul 2026 | |
| 5 | Free | 4.5★ (126K) | Yes | Yes | Jul 2026 | |
| 6 | Free | 5.0★ (1) | No | No | May 2026 | |
| 7 | Free | 4.7★ (15K) | Yes | Yes | Jul 2026 | |
| 8 | Free | 4.7★ (23K) | No | Yes | Jul 2026 |








Calculate the correct series resistor needed to safely power light-emitting diodes. Input supply voltage, LED voltage drop, current, and the number of LEDs to find the required resistor value and wattage.





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 comprehensive suite of calculation tools, including basic, scientific, and unit conversion functions. It features an AI-powered math solver that can solve problems from photos and a dedicated math notes section for jotting down equations and diagrams. Accessibility options like dynamic text size and VoiceOver support are also included.


This app offers both basic and advanced scientific calculations with an intuitive interface designed for tablets and phones. It includes features like currency conversion, calculation history, and the ability to share results. An optional premium membership removes ads and provides enhanced support.


This app simplifies selecting the right video processor for LED display projects. It offers seamless calculations, advanced filtering, and instant access to product specifications, serial number lookup, and support ticket creation.


This app offers a customizable and fast calculator experience with a wide variety of themes. It includes scientific and standard modes, real-time results, and calculation history. Personalize your math with over 60 cute and colorful themes, including animated options.


This free calculator app offers a fast, ad-free experience with a visual input and calculation history. Customize your experience with various keyboard sounds and colors, and access advanced scientific functions when needed.


A highly customizable calculator app offering a modern interface and extensive features. Personalize themes, button layouts, and visual elements. Track your calculations with a detailed history and access scientific functions.


This app offers a clean and intuitive interface for both basic arithmetic and advanced scientific calculations. It includes a history tape to review past computations and supports various mathematical operations, making it suitable for everyday use and complex problem-solving.


This app offers a versatile calculator experience with both standard and scientific modes. Customize its appearance, use it in any orientation, and access additional tools like a notes tab and calculation history. It's designed for students and professionals needing accurate calculations.


This app offers a versatile calculator with three distinct modes: Basic, Scientific, and Programmer. It provides a history view, sharing capabilities, and supports various input and output formats. The app is designed for iPhone, iPad, and iPod Touch.


This free scientific calculator offers essential features like RPN mode, unit conversions, and multiple undo/redo. It provides a taste of a more powerful version, with optional in-app purchases for expanded functionality.


This app offers a powerful scientific calculator with a wide range of functions for trigonometry, statistics, and combinatorics. Users can define and evaluate their own functions, assign values to variables, and view multiple expressions simultaneously. It works offline and is completely free to use.


A user-friendly calculator app featuring large buttons and customizable colorful backgrounds. It offers a dual-line display, multi-line input for complex equations, and convenient gesture controls for editing and copying.


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 powerful graphing calculator experience with touch-based input for enhanced interaction. It supports natural textbook notation, advanced math functions, and various plotting capabilities. Users can also utilize its programming features and built-in tools like unit conversion and a periodic table.




This app offers a user-friendly calculator experience with a focus on ease of use. It features a live voice input, an ergonomic layout with large keys, and a usage history for quick reference. Results can be easily copied or emailed.


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.