Free42 vs TechniCalc Calculator
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Free42
This app is a faithful open-source simulation of the HP-42S scientific calculator and its associated printer. It offers a complete rewrite without requiring original ROM images, allowing users to run existing programs on their mobile devices.
- HP-42S calculator simulation
- HP-82240 printer simulation
- Open-source project
- Runs original HP-42S programs
- No ROM image required
- Customizable skins
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Free42 is a re-implementation of the HP-42S calculator and the HP-82240 printer. It is a complete rewrite, not using any HP code, and it does not require an HP-42S ROM image. Free42 is an Open Source project. The executables and source code are released under the terms of the GNU General Public License, version 2. All third-party code used in Free42 is either in the public domain, or licensed under terms compatible with GPLv2, or used with the authors' permission.
TechniCalc Calculator
This app offers a modern, intuitive interface for complex calculations, supporting scientific, engineering, and advanced mathematical functions. It allows natural equation entry, provides a formula book, and includes unit and currency converters. Available across Apple devices, it caters to students and professionals needing a powerful calculation tool.
- Natural equation entry
- Advanced math engine
- Formula book and equations
- Unit and currency converter
- Statistics mode
- Equation solvers
- Supports multiple Apple devices
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TechniCalc is every bit functional as it is beautiful. The modern interface that makes a clean break from traditional pocket calculators. Equations are entered in a natural way, adhering to every detail of hand-written maths. The advanced maths engine also makes this the only calculator you'll ever need. ◉ FEATURES ▸ Runs on iPhone, iPad, and macOS - with an Apple Watch companion ▸ Dark mode ▸ Supports split screen and wireless keyboards ▸ Shows the full equation as you type ▸ Basic calculations (+, -, ×, ÷, %) ▸ Brackets ▸ Square and cubic roots ▸ Exponents and logarithms ▸ Trigonometry (sin, cos, tan) ▸ Degrees, radians, and gradians ▸ Constants (pi, e, and over 100 other physical constants) ▸ Formula book and equations ▸ Calculation history ▸ Unit converter ▸ Currency converter ▸ Statistics mode ◉ ADVANCED MATHS ▸ Almost unlimited number sizes - over 1,000,000 factorial ▸ Square roots and logarithms with any base ▸ Factorial, nPr, nCr, and gamma ▸ Hyperbolic trigonometry (sinh, cosh, tanh) ▸ Vectors and matrices ▸ Imaginary and complex numbers ▸ Series sums and products ▸ Numerical integration and differentiation ▸ Binary, octal, and hexadecimal ▸ Programmer mode ◉ EQUATION SOLVERS ▸ Quadratic ▸ Cubic ▸ Systems of 2 and 3 linear equations ▸ Root finder
Screenshots
Verdict
The clearest difference is price: Free42 at Free against TechniCalc Calculator's $7.99. Free42 also leads on in-app purchases (none vs 4) and update cadence (weekly vs monthly). On rating, ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Free42 is free to download; TechniCalc Calculator costs $7.99 up front. TechniCalc Calculator sells 4 one-off in-app purchases. Free42 asks for nothing beyond the download.
On the App Store both sit at effectively the same score — 4.8 for Free42 against 4.7 for TechniCalc Calculator. Both are backed by a comparable volume of ratings — 288 and 84 respectively. Written reviews are what separate them: 94% of Free42's written reviews are positive against 85% of TechniCalc Calculator's.
Free42 ships an update weekly, TechniCalc Calculator monthly. Both last shipped on November 13, 2026.
| Parameter | Free42 | TechniCalc Calculator |
|---|---|---|
| Price | Free — better | $7.99 |
| Rating | 4.8 (288 ratings) — better | 4.7 (84 ratings) |
| Positive reviews | 94.4% of reviews — better | 84.6% of reviews |
| Number of ratings | 288 — better | 84 |
| Update frequency | Weekly — better | Monthly |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free — better | Free with in-app purchases |
| Devices | iPhone, iPad, iPod | iPhone, iPad, Mac, Apple Watch — better |
| Requires iOS | 15.0 — better | 17.0 |
| Further details — not scored | ||
| Size | 9 MB | 31 MB |
| Age rating | 4+ | 4+ |
| Developer | Thomas Okken | Jacob Parker |
Customer experience
Free42
TechniCalc Calculator
User reviews
Free42
From 288 App Store ratingsWhat we love
- 🚀 Faithful reproduction of HP42S
- 👍 Identical to physical calculator
- 👍 Runs all original programs
- 👍 Convenient to have on phone
- 👍 Haptic feedback on button presses
Room to improve
- 🐛 Screen not filling entire display on newer devices
- 🔇 Configurable key click sound missing
- 🔇 Lack of loud click sound feedback
TechniCalc Calculator
From 84 App Store ratingsWhat we love
- ✨ Beautiful and clean UI
- 🚀 Powerful and versatile functionality
- 👍 Intuitive and easy to use
- 💡 Extensive features for scientific and basic use
- 👨💻 Responsive and dedicated developer
Room to improve
- 🐛 Interface scaling issues on iPad (split screen/windowed mode)
- 🐛 UI elements (keypad, sidebar) become enormous when resized
- 🐛 Calculations get squished at the top of the window
- 🐛 Matrices overlap on themselves when resized
- 🐛 Text too small and light on iPad
Bugs and requests
Free42
Reported bugs
2 issues- Occasional issues with Solver function
- Store and Recall functions not working properly
Requested features
3 requests- Display all registers (X, Y, Z, T, Last X) simultaneously
- Ability to share/transfer programs between devices
- Improved use of screen real estate on larger displays
TechniCalc Calculator
Reported bugs
18 issues- Interface scaling issues on iPad (split screen/windowed mode)
- UI elements (keypad, sidebar) become enormous when resized
- Calculations get squished at the top of the window
- Matrices overlap on themselves when resized
- Text too small and light on iPad
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- Unit converter is time-consuming to change units
- Matrix dimensions are not always possible (e.g., 3x2)
- Lacks basic matrix functions like reducedRowEchelon
- Complicated to use for some matrix operations
- No real instruction manual, reference section incomplete
- Inconsistencies in signs with decimal numbers (magnitude correct, sign always positive)
- Some calculations can be slow after currency update
- Real and imaginary breakout functions have strange behavior
- Window size cannot be changed on macOS
- Cannot force quit on macOS, requires restart
- Not easily findable on macOS
- No way to leave a second tip for the developer
- Resent not being able to email the developer directly
Requested features
15 requests- Functionality on Apple Watch
- Option to change divide sign to /
- Multi-line history on the top
- Color coding for grouped buttons
- More interface customization
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- Option to color the background of calculator buttons
- Widget for quick access
- Favorites menu for unit conversions
- Syncing of saved equations and settings across devices
- Easier way to solve for a parameter in an equation without initial guesses
- Export operations as LaTeX
- Decimal to mixed number form conversion
- Unlock different background colors/themes and app icons
- Adjust font size to be bolder and larger on iPad
- Improved functionality in low light and outside
In-app purchases
Free42
No in-app purchases
TechniCalc Calculator
- Every Little Helps$0.99
- Coffee-Sized Tip$2.99
- Lunch-Sized Tip$4.99
Show 1 moreShow fewer
- Pizza-Sized Tip$9.99








