Unit Converter MCP

Unit conversion utilities that provide precise conversions between different units of measurement.

🔧 Tools

🔧 Examples

Here are some example prompts to get you started:

convert 0 celsius to fahrenheit

what's my weight in kg? I'm 205lbs

convert 3.14159 radians to degrees

convert the speed of a snail to Mach

how many floppy disks do you need to store 1TB?

how much area would 1,000 mattresses take up in acres

how many non-stop days would it take to watch Game of Thrones?

🔧 Setup

Claude Desktop

Add this to your Claude Desktop configuration file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "unit-converter": {
      "command": "uvx",
      "args": ["unit-converter-mcp"]
    }
  }
}

📋 Tool Reference

convert_temperature

Convert temperature between Celsius, Fahrenheit, and Kelvin.

Parameters:

• value (float): Temperature value to convert
• from_unit (str): Source unit (celsius, fahrenheit, kelvin)
• to_unit (str): Target unit (celsius, fahrenheit, kelvin)

Example:

{
  "name": "convert_temperature",
  "arguments": {
    "value": 100,
    "from_unit": "celsius",
    "to_unit": "fahrenheit"
  }
}

convert_length

Convert length between various units including metric and imperial systems.

Parameters:

• value (float): Length value to convert
• from_unit (str): Source unit (meter, kilometer, centimeter, millimeter, inch, foot, yard, mile)
• to_unit (str): Target unit (meter, kilometer, centimeter, millimeter, inch, foot, yard, mile)

Example:

{
  "name": "convert_length",
  "arguments": {
    "value": 1,
    "from_unit": "meter",
    "to_unit": "foot"
  }
}

convert_mass

Convert mass between various units including metric, imperial, and specialized units.

Parameters:

• value (float): Mass value to convert
• from_unit (str): Source unit (kilogram, gram, pound, ounce, tonne, carat, stone, etc.)
• to_unit (str): Target unit (kilogram, gram, pound, ounce, tonne, carat, stone, etc.)

Supported Units:

• Metric: kilogram, gram, milligram, microgram, nanogram, picogram, femtogram, decagram, hectogram, tonne, kilotonne, megatonne
• Imperial: pound, ounce, stone, short ton (US), long ton (UK)
• Precious metals: troy ounce, carat
• Historical: grain

Example:

{
  "name": "convert_mass",
  "arguments": {
    "value": 1,
    "from_unit": "kilogram",
    "to_unit": "pound"
  }
}

convert_volume

Convert volume between various units including metric and imperial systems.

Parameters:

• value (float): Volume value to convert
• from_unit (str): Source unit (liter, milliliter, gallon, quart, pint, cup, fluid_ounce)
• to_unit (str): Target unit (liter, milliliter, gallon, quart, pint, cup, fluid_ounce)

Example:

{
  "name": "convert_volume",
  "arguments": {
    "value": 1,
    "from_unit": "liter",
    "to_unit": "gallon"
  }
}

convert_time

Convert time between various units from sub-seconds to millennia.

Parameters:

• value (float): Time value to convert
• from_unit (str): Source unit (seconds, minutes, hours, days, weeks, months, years, etc.)
• to_unit (str): Target unit (seconds, minutes, hours, days, weeks, months, years, etc.)

Example:

{
  "name": "convert_time",
  "arguments": {
    "value": 1,
    "from_unit": "hours",
    "to_unit": "minutes"
  }
}

convert_energy

Convert energy between various units including metric, electrical, heat, nutrition, and particle physics systems.

Parameters:

• value (float): Energy value to convert
• from_unit (str): Source unit (joule, kilowatt hour, calorie, Btu, etc.)
• to_unit (str): Target unit (joule, kilowatt hour, calorie, Btu, etc.)

Supported Units:

• SI and metric prefixes: joule, kilojoule, megajoule, gigajoule, terajoule, petajoule, exajoule
• Electrical-energy units: watt hour, kilowatt hour, megawatt hour, gigawatt hour, terawatt hour
• Heat / nutrition: Btu, calorie, kilocalorie, therm
• Mechanical & particle-physics units: foot‑pound force, inch‑pound force, erg, electron volt

Example:

{
  "name": "convert_energy",
  "arguments": {
    "value": 1,
    "from_unit": "kilowatt hour",
    "to_unit": "joule"
  }
}

convert_force

Convert force between various units including metric and imperial systems.

Parameters:

• value (float): Force value to convert
• from_unit (str): Source unit (newtons, pounds force, kilograms force, dynes, kilonewtons, kips, etc.)
• to_unit (str): Target unit (newtons, pounds force, kilograms force, dynes, kilonewtons, kips, etc.)

Supported Units:

• Metric: newtons, kilonewtons, meganewtons, dynes
• Imperial: pounds force, kips
• Other: kilograms force, tonnes force, long tons force, short tons force

Example:

{
  "name": "convert_force",
  "arguments": {
    "value": 100,
    "from_unit": "newtons",
    "to_unit": "pounds force"
  }
}

convert_density

Convert density between various units including metric, imperial, and specialized systems.

Parameters:

• value (float): Density value to convert
• from_unit (str): Source unit (kilograms per liter, grams per cubic centimeter, pounds per gallon, etc.)
• to_unit (str): Target unit (kilograms per liter, grams per cubic centimeter, pounds per gallon, etc.)

Supported Units:

• Grain-based hardness units: grains per gallon (UK), grains per gallon (US), grains per gallon
• Metric staples: grams per cubic centimeter, grams per liter, kilograms per liter, kilograms per cubic meter, milligrams per liter
• Fluid-ounce units: ounces per gallon (UK), ounces per gallon (US), ounces per gallon
• Pound-based units: pounds per cubic foot, pounds per gallon (UK), pounds per gallon (US), pounds per gallon
• Tonne/ton bulk-density units: tonnes per cubic meter, tons per cubic yard (UK), tons per cubic yard (US), tons per cubic yard

Example:

{
  "name": "convert_density",
  "arguments": {
    "value": 1,
    "from_unit": "kilograms per liter",
    "to_unit": "grams per cubic centimeter"
  }
}

list_supported_units

List all supported units for each conversion type.

Parameters: None

Example:

{
  "name": "list_supported_units",
  "arguments": {}
}

convert_angle

Convert angle between degrees, radians, and other angular units.

Parameters:

• value (float): Angle value to convert
• from_unit (str): Source unit (degrees, radians, arcmin, arcsec, turns, gons)
• to_unit (str): Target unit (degrees, radians, arcmin, arcsec, turns, gons)

Example:

{
  "name": "convert_angle",
  "arguments": {
    "value": 3.14159,
    "from_unit": "radians",
    "to_unit": "degrees"
  }
}

convert_area

Convert area between various units including metric and imperial systems.

Parameters:

• value (float): Area value to convert
• from_unit (str): Source unit (acre, are, hectare, square centimeter, square foot, square inch, square kilometer, square meter, square mile, square millimeter, square yard)
• to_unit (str): Target unit (acre, are, hectare, square centimeter, square foot, square inch, square kilometer, square meter, square mile, square millimeter, square yard)

Example:

{
  "name": "convert_area",
  "arguments": {
    "value": 1,
    "from_unit": "hectare",
    "to_unit": "acre"
  }
}

convert_computer_data

Convert computer storage between various units from bits to exabytes.

Parameters:

• value (float): Computer storage value to convert
• from_unit (str): Source unit (bits, bytes, kilobytes, megabytes, gigabytes, terabytes, petabytes, exabytes)
• to_unit (str): Target unit (bits, bytes, kilobytes, megabytes, gigabytes, terabytes, petabytes, exabytes)

Example:

{
  "name": "convert_computer_data",
  "arguments": {
    "value": 1,
    "from_unit": "gigabytes",
    "to_unit": "megabytes"
  }
}

convert_pressure

Convert pressure between various units including metric, imperial, and specialized systems.

Parameters:

• value (float): Pressure value to convert
• from_unit (str): Source unit (pascal, hectopascal, kilopascal, megapascal, bar, atmosphere, centimeters of water, inches of water, feet of water, meters of water, millimeters of mercury, inches of mercury, kilogram force per square centimeter, newtons per square centimeter, newtons per square millimeter, psi, psf)
• to_unit (str): Target unit (pascal, hectopascal, kilopascal, megapascal, bar, atmosphere, centimeters of water, inches of water, feet of water, meters of water, millimeters of mercury, inches of mercury, kilogram force per square centimeter, newtons per square centimeter, newtons per square millimeter, psi, psf)

Example:

{
  "name": "convert_pressure",
  "arguments": {
    "value": 1,
    "from_unit": "atmosphere",
    "to_unit": "psi"
  }
}

convert_power

Convert power between various units including mechanical, electrical, and thermal systems.

Parameters:

• value (float): Power value to convert
• from_unit (str): Source unit (Btu per hour, foot pound‑force per second, ton of refrigeration, calorie per hour, kilocalorie per hour, horsepower, horsepower (metric), kilogram‑force meter per second, watt, kilowatt, megawatt, gigawatt, terawatt, petawatt)
• to_unit (str): Target unit (Btu per hour, foot pound‑force per second, ton of refrigeration, calorie per hour, kilocalorie per hour, horsepower, horsepower (metric), kilogram‑force meter per second, watt, kilowatt, megawatt, gigawatt, terawatt, petawatt)

Example:

{
  "name": "convert_power",
  "arguments": {
    "value": 1,
    "from_unit": "horsepower",
    "to_unit": "kilowatt"
  }
}

convert_speed

Convert speed between various units including metric, imperial, and specialized systems.

Parameters:

• value (float): Speed value to convert
• from_unit (str): Source unit (centimeters per minute, centimeters per second, feet per hour, feet per minute, feet per second, inches per minute, inches per second, kilometers per hour, kilometers per second, knots, Mach (ISA sea level), speed of sound, meters per hour, meters per minute, meters per second, miles per hour, miles per minute, miles per second, yards per hour, yards per minute, yards per second, speed of light)
• to_unit (str): Target unit (centimeters per minute, centimeters per second, feet per hour, feet per minute, feet per second, inches per minute, inches per second, kilometers per hour, kilometers per second, knots, Mach (ISA sea level), speed of sound, meters per hour, meters per minute, meters per second, miles per hour, miles per minute, miles per second, yards per hour, yards per minute, yards per second, speed of light)

Example:

{
  "name": "convert_speed",
  "arguments": {
    "value": 60,
    "from_unit": "miles per hour",
    "to_unit": "meters per second"
  }
}

🛠️ Development

Prerequisites

• Python 3.10+
• uv package manager

Setup

# Clone the repository
git clone https://github.com/zazencodes/unit-converter-mcp
cd unit-converter-mcp

# Install dependencies
uv sync --dev

# Run tests
uv run pytest

# Run linting
uv run ruff check --fix
uv run ruff format

# Type checking
uv run mypy src/

MCP Client Config

{
  "mcpServers": {
    "unit-converter-dev": {
      "command": "uv",
      "args": [
        "--directory",
        "<path_to_your_repo>/unit-converter-mcp",
        "run",
        "unit-converter-mcp"
      ]
    }
  }
}

Note: Replace <path_to_your_repo>/unit-converter-mcp with the absolute path to your cloned repository.

Building

# Build package
uv build

# Test installation
uv run --with dist/*.whl unit-converter-mcp

Release Checklist

1. Update Version:

   • Increment the version number in pyproject.toml and src/__init__.py.

2. Update Changelog:

   • Add a new entry in CHANGELOG.md for the release.

     • Draft notes with coding agent using git diff context.

     Update the @CHANGELOG.md for the latest release.
     List all significant changes, bug fixes, and new features.
     Here's the git diff:
     [GIT_DIFF]
     

   • Commit along with any other pending changes.

3. Create GitHub Release:

   • Draft a new release on the GitHub UI.
     • Tag release using UI.
   • The GitHub workflow will automatically build and publish the package to PyPI.

Testing with MCP Inspector

For exploring and/or developing this server, use the MCP Inspector npm utility:

# Install MCP Inspector
npm install -g @modelcontextprotocol/inspector

# Run local development server with the inspector
npx @modelcontextprotocol/inspector uv run unit-converter-mcp

# Run PyPI production server with the inspector
npx @modelcontextprotocol/inspector uvx unit-converter-mcp

📝 License

MIT License - see LICENSE file for details.

🤝 Contributing

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