66 calculators in one Android app — a fast everyday keypad, a full calculus workbench, an electrical circuit editor, and an AI that reads a photograph of a problem.
| Main menu | Scientific calculator | Calculus graph |
|---|---|---|
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| The landing screen: quick arithmetic, search across all 66 tools, and eight categories. | DEG/RAD/GRAD, the full function keypad, memory keys and collapsible reference panels. |
Interactive plot with pan, pinch-zoom, an optional f′ layer and a shaded-area limit. |
Calculator Suite is a single-purpose Android app that bundles 66 registered tools across 8 categories, plus an everyday keypad, a full scientific calculator, an electrical circuit editor that works out the circuits you draw, and an AI problem solver that reads a photograph of a mathematical problem and works it out with the app's own engines. Everything is written in Kotlin with Jetpack Compose (Material 3).
The design goal was no dead controls: every button, field and toggle performs a real computation with exact arithmetic where the mathematics allows it, and shows its working rather than a bare number.
- Exact where it can be. Money and general decimals use
BigDecimalwith a 34-significant-digit evaluation context; integer maths (factorials, GCD/LCM, primes, permutations) usesBigInteger. Display rounding happens only at the very end, at 3–15 significant digits. - Honest about approximations. Numerical results are prefixed
≈and their method is named — adaptive Simpson for definite integrals, RK4 for differential equations, bisection for root scans. - On-device by default. Every tool works with the device in aeroplane mode. The only network calls are the currency converter fetching reference exchange rates, and the AI problem solver talking to the provider you chose — the picture goes nowhere else, and only when you press the button.
- Nothing to sign up for. There is no account, no advert, no tracker, no crash reporter and no telemetry. The app asks for no permission beyond the network, the AI feature is off until you turn it on, and the one thing it stores is on your own device.
| 🧮 Everyday keypad | Live preview as you type, four memory keys, optional full-screen expansion. |
| 🔬 Scientific calculator | Trig, logs, powers, factorials, mod, memory, DEG/RAD/GRAD, and collapsible reference panels that match the keypad exactly. |
| ∫ Calculus workbench | Fourteen focused tools: derivatives, integrals, limits, Taylor/Maclaurin, Σ and Π notation, infinite series, roots, extrema, an interactive function graph, differential equations, multivariable calculus, Fourier analysis, complex analysis and partial differential equations. |
| ⚡ Electrical Circuits | Draw a circuit on a canvas — resistors, sources, switches and a ground — wire it up, and the app solves it by nodal analysis and shows the voltage, current and power of every part, with the working. Eleven electrical calculators come with it. |
| 🧠 AI problem solver | Photograph a mathematical problem. The AI reads it, picks the right Calculator Suite tool, and the app's own engine does the mathematics. Ten providers, your own key, your own model. |
| 🚫 No sign-up, no adverts, no tracking | Nothing to create an account for, nothing sold, and every tool works with the network off. |
| 📐 Advanced mathematics | Measure theory, a topology explorer and functional analysis — each computing real values and stating what it does not reach. |
| 🎨 Accent colour | A palette of presets or a custom colour of your own, reaching every button, surface, curve and highlight in the app. |
| 📐 23 converters | Length, area, volume, mass, temperature, pressure, energy, power, force, torque, speed, acceleration, time, angle, data storage, data transfer, flow, fuel economy, numeric bases, Roman numerals, cooking measures, ring sizes, shoe sizes. |
| 💷 6 finance tools | Currency (live reference rates + offline cache), loan amortisation, compound interest with EAR, sales tax, tips with cent allocation, unit price comparison. |
| 🩺 3 health tools | BMI, caloric burn from MET values, US Navy body-fat estimate. |
| 📅 3 date & time tools | Exact age, date arithmetic, time intervals. |
| 🔍 Search | Every tool is findable by name or by the words people actually use — mortgage, kcal, octal, tip. |
| ⭐ Favourites & history | Starred tools and a local calculation history, both stored on-device. |
| 🌓 Light, dark & dynamic colour | Follows the system theme, or Android 12+ wallpaper colours. |
| 🇪🇺 Thousands separator | Choose automatic, comma, period, space or apostrophe — display only, never affecting how input is parsed. |
| 🛠️ Check for updates in the app | The settings screen asks the project's GitHub release page whether a newer version exists, downloads it and hands it to Android's installer, which asks you to confirm. The About screen shows what changed in the newest release. |
| 🔒 Portrait-only | Locked to portrait app-wide, so no screen or dialog ever rotates unexpectedly. |
Download the signed APK from the GitHub Release and install it.
# Verify the download before installing
sha256sum -c CalculatorSuite-v3.0.3.apk.sha256
# Install over USB
adb install CalculatorSuite-v3.0.3.apkRequirements: any phone or tablet running Android 8.0 (API 26) or newer, arm64-v8a or x86_64. It is a single APK, about 14 MB, with nothing to sign up for. You will need to allow installation from your file manager the first time.
The 3.0.3 APK is signed with the same key as 3.0.2, 3.0.1, 3.0.0, 2.0.0 and 1.0.0, so it installs straight over the older version with your settings and history intact.
- Quick maths — type on the keypad. The result previews live as you type; press
=to commit it to history. - Find a tool — tap the search field and type what you want ("tip", "hex", "mortgage"), or browse a category card.
- Enter data — most tools recompute live; the rest have an explicit Calculate button. Every tool has a Reset action in its top bar that restores that tool's defaults.
- Copy or save — every result card can copy a full-precision value or push the calculation into history.
- Adjust behaviour — open Settings for theme, accent colour, angle unit, result precision, thousands separator, haptics and wallpaper colours.
- Build a circuit — open Electrical Circuits, put parts on the canvas, wire them together and press Calculate the circuit; the app solves the circuit from its own equations and explains how it got there.
- Let the AI read a problem — tap the brain button, photograph a mathematical problem or pick a picture of one, and the app works it out. You choose the provider, the model and your own key in the AI settings; see the User Guide.
Number entry accepts 1 234,56 and 1,234.56 interchangeably; the decimal mark always follows your device's region. See the User Guide for input rules, error messages and common workflows.
You need JDK 17 or newer (JDK 21 is what CI uses) and an Android SDK with API 36 installed. Point Gradle at it with a local.properties file containing sdk.dir=/path/to/Android/sdk, or set ANDROID_HOME.
git clone https://github.com/JuggyBob/CalculatorSuiteAndroid.git
cd CalculatorSuiteAndroid
./gradlew :app:testDebugUnitTest # 1464 JVM unit tests
./gradlew :app:lintDebug # Android Lint
./gradlew :app:assembleDebug # app/build/outputs/apk/debug/app-debug.apkFull instructions, build variants and troubleshooting are in docs/BUILDING.md.
| Layer | Choice |
|---|---|
| Language | Kotlin 2.2.10 |
| UI | Jetpack Compose (Material 3), Compose BOM 2026.05.01 |
| Navigation | Navigation Compose 2.8.9 |
| Architecture | MVU-style CalcResult<T> result type, single-Activity Compose navigation graph |
| Persistence | DataStore Preferences 1.1.7 |
| Numerics | java.math.BigDecimal / BigInteger (34-digit MathContext), Double for numerical calculus |
| Dates | java.time |
| Networking | HttpURLConnection + org.json (currency rates, and the AI provider you choose) |
| Build | Gradle 8.13, Android Gradle Plugin 8.13.2, Kotlin Compose plugin |
| Tests | JUnit 4 on the JVM — 1410 tests, no instrumentation required |
| Min / target SDK | 26 / 36 |
See docs/DEPENDENCIES.md for the full list with licences, and docs/ARCHITECTURE.md for how the code is organised.
| Features & tools | Every one of the 66 tools, with inputs, formulas, limits and worked examples |
| User guide | Navigation, input rules, settings, history, error messages |
| Calculus guide | Expression syntax, each operation, graphing, and the honest limits of the symbolic engine |
| Architecture | Package layout, engines, navigation, state, testing strategy |
| Building | Prerequisites, Gradle tasks, variants, troubleshooting |
| Dependencies | Every dependency, its version, purpose and licence |
| FAQ | Compatibility, accuracy and privacy questions |
| Roadmap | What is implemented, what is outstanding, what might come next |
| Changelog | Release history |
| Contributing | Development setup and conventions |
Calculator Suite is offline-first and does not collect, transmit or sell any personal data. There is no analytics, no advertising, no tracking SDK and no account. All history, favourites and settings stay in the app's private local storage.
There are two features that talk to the internet, and both are opt-in and visible:
- The Currency converter makes a single HTTPS request to
open.er-api.com(a free, key-less public rate service) to fetch reference exchange rates. Nothing about you is sent beyond the currency you select as the base. Rates are cached locally so the tool keeps working offline, and the app shows a warning when the cache is more than 24 hours old. - The AI problem solver sends the picture and the question to the AI provider you chose in the settings — OpenAI, Anthropic, Google Gemini, OpenRouter, DeepSeek, Groq, Mistral AI, xAI, Together AI or Fireworks AI. Your API key is kept by the phone's own keystore, encrypted, and never written in plain text or included in an error message. The picture is only ever sent to the provider you selected, and only when you press the button. If you never configure the AI feature, nothing about you is ever sent anywhere.
That is the whole list. There is no third-party SDK that collects anything, and the app has no account system.
Full details — including the complete permission list and exactly what is stored on disk — are in PRIVACY.md.
Calculator Suite is source-available software released under the PolyForm Noncommercial License 1.0.0. It is not OSI-approved open source.
In plain English:
- ✅ You may read, run, study, modify and redistribute the software for any noncommercial purpose — personal, educational, hobby, research, or inside a charity, school, public body or government institution.
- ✅ You may build and distribute modified versions for noncommercial purposes, provided you keep this license and its notices.
- ❌ You may not use it, or a derivative of it, for a commercial purpose — including selling it, bundling it into a paid product, or running it as part of a revenue-generating service. The software being free of charge does not make commercial use permitted.
Note that this license covers this project's code only. Third-party libraries keep their own licences, which are listed in docs/DEPENDENCIES.md.
© JuggyBob. Calculator Suite is licensed under the PolyForm Noncommercial License 1.0.0.
Contributions are welcome — bug reports, documentation fixes and code alike. See CONTRIBUTING.md for the setup and the project's coding conventions, CODE_OF_CONDUCT.md for community expectations, and SECURITY.md if you have found a vulnerability rather than a bug.
Open an issue using one of the templates. If a calculator returns a wrong number, please include the exact input and the result you expected — that is the single most useful thing you can send.