Coinbase PnL Calculator

A Go-based tool for calculating Profit and Loss (PnL) from Coinbase Advanced Trade futures orders using FIFO (First In First Out) accounting.

Overview

This tool fetches your Coinbase Advanced Trade futures trading history and generates daily PnL reports using FIFO position tracking.

Features

• FIFO Position Tracking: Matches buy and sell orders using First In First Out methodology
• Futures Contract Support: Handles different contract multipliers (e.g., ETP: 0.1x, XPP: 500x)
• Daily PnL Reports: Generates JSON reports with daily profit/loss by month
• API Integration: Fetches data from Coinbase Advanced Trade API
• Fee Accounting: Includes trading fees in PnL calculations

Prerequisites

• Go 1.24.1 or higher
• Coinbase Advanced Trade account with API credentials
• Active or historical futures trading activity

Installation

1. Clone the repository:

git clone https://github.com/yourusername/coinbase-pnl-calculator.git
cd coinbase-pnl-calculator

2. Install dependencies:

go mod download

3. Set up your environment variables:

cp .env.example .env

4. Edit .env and add your Coinbase API credentials:

KEY_NAME=your_api_key_name
KEY_SECRET=your_api_private_key

Getting Coinbase API Credentials

1. Log in to Coinbase Advanced Trade
2. Navigate to Settings → API
3. Create a new API key with the following permissions:
   • View: Trading history
   • Trade: Not required
4. Copy the Key Name and Private Key to your .env file

Usage

Run the calculator:

go run .

The tool will:

1. Fetch all filled futures orders from Coinbase API
2. Process orders chronologically using FIFO methodology
3. Calculate daily PnL for each trading day
4. Generate pnl_report.json with monthly breakdowns

Output Format

The generated pnl_report.json contains monthly data structured as:

{
  "2025-08": {
    "month": "August",
    "year": 2025,
    "days": [
      {
        "date": "2025-08-01",
        "pnl": -308.67,
        "tradeCount": 5,
        "hasNotes": false
      }
    ]
  }
}

Report Fields

• month: Month name
• year: Year
• days: Array of daily PnL entries
  • date: ISO 8601 date (YYYY-MM-DD)
  • pnl: Realized profit/loss for the day (USD)
  • tradeCount: Number of trades executed
  • hasNotes: Flag for manual notes (currently always false)

How FIFO Works

The calculator uses FIFO (First In First Out) position tracking:

1. Buy Orders: Create positions in a queue with entry price and size
2. Sell Orders: Match against oldest positions first
3. PnL Calculation: (sell_price - entry_price) × size - fees
4. Partial Fills: Handles partial position closures correctly

Example

BUY  1.0 BTC @ $50,000  → Position queue: [1.0 @ $50,000]
BUY  0.5 BTC @ $51,000  → Position queue: [1.0 @ $50,000, 0.5 @ $51,000]
SELL 1.2 BTC @ $52,000  → Matches: 1.0 @ $50k + 0.2 @ $51k
                        → PnL: (52k - 50k) × 1.0 + (52k - 51k) × 0.2 - fees

Project Structure

.
├── main.go         # Application entry point and orchestration
├── auth.go         # JWT authentication for Coinbase API
├── fetcher.go      # API client for fetching orders
├── pnl.go          # FIFO PnL calculation engine
├── report.go       # Report generation and formatting
├── types.go        # Data structure definitions
├── go.mod          # Go module dependencies
└── .env            # API credentials (not in git)

Development

Building

go build -o coinbase-pnl-calculator .

Running the Binary

./coinbase-pnl-calculator

License

MIT License - See LICENSE file for details

Disclaimer

This tool is for informational purposes only. Always consult with a tax professional for official tax reporting. The authors are not responsible for any financial decisions made based on this tool's output.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Support

For issues or questions, please open an issue on GitHub.