Best Retro 15C alternatives: apps like Retro 15C

10+ similar apps compared and reviewed

4.4 avg rating

7 free apps

Updated October 2026

Greg Hewgill

Retro 15C is great, but it's not the only option. Explore 10+ similar apps for iPhone and iPad, each reviewed and rated by real users. Find free alternatives, premium upgrades, and hidden gems.

Top Alternatives to Retro 15C

#1

Free42 by Thomas Okken

HP-42S Calculator Simulator

Editor's Choice

4.8😊(283 ratings)

Free

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This application is a faithful re-implementation of the HP-42S scientific calculator and its associated printer. It offers full functionality without requiring original HP ROM images and is an open-source project.

What We Love

🚀 Faithful reproduction of HP42S
👍 Identical to physical calculator
👍 Runs all original programs
👍 Convenient to have on phone
👍 Haptic feedback on button presses
👍 Customizable skins
👍 Actively maintained and updated

Room to Improve

🐛 Screen not filling entire display on newer devices
🔇 Configurable key click sound missing
🔇 Lack of loud click sound feedback

#2

12C Platinum Calculator by 国栋焦

12C Platinum Calculator

Strong Contender

5.0(2 ratings)

Free

12C Platinum Calculator screenshot 1

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This financial calculator offers over 120 built-in functions for complex calculations like IRR and NPV. It supports RPN entry, programming custom keystrokes, and includes features for loan payments, interest rate conversions, bond pricing, and statistical analysis.

#3

RLM-11CX by R.L.M. Software

Scientific & Programable

Worth Considering

3.1(7 ratings)

FreeIn-App Purchases

RLM-11CX screenshot 1

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This app is a scientific and programmable calculator designed for science and engineering, replicating the functionality of the HP-11C. It offers extensive features for finance, business, statistics, complex numbers, and unit conversions, with a programmable interface for custom calculations.

More apps like Retro 15C

HP15C: Scientific Calculator

HP15C: Scientific Calculator

HP15C: Scientific Calculator

Classic Science Calc for you

Relive the classic computing experience with a vintage scientific calculator. This app emulates a beloved 90s model, offering a nostalgic and functional tool for calculations.

Vintage scientific calculator emulationClassic 90s designFunctional for scientific calculations

Compare with Retro 15C

RPN Calculator. HP-35, 45, 21

Emulates classic Hewlett Packard RPN scientific calculators from the 1970s. Experience the original HP-35, HP-45, and HP-21 models on your iPhone.

RPN calculator emulationHP-35 modelHP-45 model

Compare with Retro 15C

HP 15c Calculator

HP 15c Calculator

HP 15c Calculator

Official emulator of HP 15c

Experience the official emulator of the legendary HP 15c scientific calculator. This app offers a redesigned interface and modern look while preserving the precision and reliability of the original. It features RPN input, matrix calculations, complex functions, and numerical integration for professionals and students.

Official HP 15c emulatorRPN (Reverse Polish Notation)Matrix calculations

Compare with Retro 15C

Enhanced HP-42S Calc Simulator

This advanced scientific calculator simulates the classic HP-42S RPN calculator with enhanced features. It offers algebraic expressions, unit conversions, directories for storage, a larger resizable display, financial functions, and 2D plotting with integral and root finding.

HP-42S RPN calculator simulationAlgebraic expressionsAttached units and conversions

Compare with Retro 15C

The Best Calculator

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.

Optional RPN modeMultiple undo and redoUnit conversions and constants

free with in-app purchases

Compare with Retro 15C

Calc Pro - The Best Calculator

Calc Pro - The Best Calculator

Calc Pro - The Best Calculator

10 Calculators & Converters

This app offers a comprehensive suite of 10 powerful calculators and 10 financial worksheets, designed to handle everything from basic arithmetic to complex scientific and financial calculations. It includes features like unit conversion, currency exchange, graphing, and statistical analysis, making it a versatile tool for students and professionals.

10 powerful calculators (Standard, Scientific, Graphing, etc.)10 financial worksheets (Mortgage, Loan, Compound Interest, etc.)Unit Converter with 3000+ conversions

free with in-app purchases

Compare with Retro 15C

by Paul Wilkins

This utility app functions as a Reverse Polish Notation calculator. It handles complex numbers and utilizes extended precision for all calculations, offering an unlimited stack depth and an undo feature for up to 10 operations.

Reverse Polish Notation (RPN) inputComplex number calculationsExtended precision math

Compare with Retro 15C