Insulin Calculator

A fast, private insulin dose calculator for Android — built by a parent of a child with Type 1 diabetes.

Screenshots

Features

• Insulin Dose Calculation — Computes carb dose, correction dose, and total dose based on your inputs
• Dexcom CGM Trend Arrows — Factor in glucose trends (from rapidly rising to rapidly falling) for more accurate dosing
• Multiple Profiles — Create profiles for breakfast, lunch, dinner, etc. with per-profile carb ratio, correction factor, and target
• 24-Hour Schedule — Assign profiles to time ranges for automatic switching throughout the day
• Dose Rounding — Round to 1u, 0.5u, 0.1u, or 0.05u to match your pen or pump precision
• mg/dL & mmol/L — Switch glucose units anytime; all values and trend adjustments update automatically
• Dark & Light Themes — Dark mode, light mode, or auto (follows system setting)
• 100% Private — No accounts, no data collection, no internet required. All data stays on your device.

Building from Source

Prerequisites

• JDK 17+
• Android SDK 35 (platform + build-tools)

Build

# Debug APK
./gradlew assembleDebug

# Release AAB (requires signing config — see below)
./gradlew bundleRelease

Signing

Release builds require a keystore.properties file in the project root:

storeFile=../your-keystore.jks
storePassword=your-password
keyAlias=your-alias
keyPassword=your-password

This file is gitignored and never committed.

Project Structure

InsulinCalc/
├── app/
│   ├── build.gradle.kts              # App build config + signing
│   └── src/main/
│       ├── AndroidManifest.xml
│       ├── java/.../MainActivity.kt  # WebView host activity
│       ├── assets/                   # Web app (HTML/CSS/JS)
│       │   ├── index.html
│       │   ├── css/style.css
│       │   ├── js/app.js
│       │   └── img/
│       └── res/                      # Android resources (icons, themes)
├── tests/                            # Playwright UI tests
├── store-assets/                     # Play Store screenshots & graphics
├── build.gradle.kts                  # Root build config
└── settings.gradle.kts

Architecture

The app uses a native Android WebView to host the calculator UI. The core logic is vanilla HTML/CSS/JS — no frameworks, no dependencies, no network calls. The native Kotlin shell handles the splash screen, system bar theming, and edge-to-edge display.

Testing

UI tests use Playwright across 6 device viewports:

npm install
npx playwright test

To regenerate Play Store screenshots:

npx playwright test tests/screenshots.spec.js --project="Pixel 5"

Disclaimer

This app helps you make insulin dosing calculations. You are strongly encouraged to confirm any information with your professional healthcare provider. This app is not a medical device and is not intended to replace professional medical advice. Not associated with Dexcom or any other medical provider. For medical emergencies call 911.

License

MIT