Barbell Load Calculator

Cross-platform application that helps weightlifters calculate optimal plate distribution for barbell exercises. Available as a web app (Solid.js) and mobile app (React Native/Expo).

Features

• Calculate plate distribution for target weight
• Select available plate weights
• Choose barbell type (45 lb or 33 lb)
• Percentage calculator for training programs
• Manual plate counter
• Light/dark theme support
• State persistence across sessions

Monorepo Structure

packages/
  shared/      # Framework-agnostic calculation logic & types
  web/         # Solid.js web application
  mobile/      # React Native + Expo mobile application

Shared Package (@barbell/shared)

• Pure TypeScript calculation logic
• Type definitions (BarWeight, PlateWeight, PlatePair)
• Constants (storage keys, input constraints)
• Framework-agnostic, used by both web and mobile

Web Package (@barbell/web)

• Solid.js 1.9.10
• TypeScript 5.9.3 (strict mode)
• Vite 5.4.21
• Tailwind CSS 4.1.17 + DaisyUI 5.4.7

Mobile Package (@barbell/mobile)

• React Native 0.76.9
• Expo SDK 52
• Expo Router 4.0 (file-based routing)
• Zustand 5.0.3 (state management)
• NativeWind 4.1.28 (Tailwind for RN)
• AsyncStorage persistence

Development

Prerequisites

• Node.js 18+
• pnpm 8+

Installation

pnpm install

Available Scripts

Run Web App:

pnpm dev:web

Opens at http://localhost:5173

Run Mobile App:

pnpm dev:mobile

Then press i for iOS simulator or a for Android emulator

Build All Packages:

pnpm build:all

TypeScript Check:

pnpm typecheck

Run Tests:

pnpm test

Package-Specific Commands

Web:

pnpm --filter @barbell/web dev
pnpm --filter @barbell/web build
pnpm --filter @barbell/web serve

Mobile:

pnpm --filter @barbell/mobile start
pnpm --filter @barbell/mobile ios
pnpm --filter @barbell/mobile android

Shared:

pnpm --filter @barbell/shared test
pnpm --filter @barbell/shared test:watch

Testing

Unit tests for shared calculation logic:

cd packages/shared
pnpm test

15 test cases covering:

• Basic calculations (135, 225, 315 lb)
• Edge cases (target < barbell, no plates)
• Multiple plate types
• Barbell weight variations (33/45 lb)
• Disabled plates
• Greedy algorithm verification
• Fractional plates (0.25, 0.5 lb)
• Max weight scenarios

Deployment

Web

Deploy packages/web/dist to Vercel, Netlify, or any static host.

Mobile

Use EAS Build:

cd packages/mobile
eas build --platform ios
eas build --platform android

Architecture

State Management

• Web: Solid.js createStore with localStorage
• Mobile: Zustand with AsyncStorage persistence

Shared Logic

Both platforms import from @barbell/shared:

import { calculatePlates, type PlateWeight } from '@barbell/shared';

Calculation Algorithm

Greedy algorithm using largest plates first:

1. Sort enabled plates by weight (descending)
2. For each plate, add as many pairs as fit
3. Return plate distribution per side

License

MIT