Quickstart

rink Quickstart

Rink is a unit-aware calculator with dimensionality analysis for physics and engineering calculations. Use this skill when you need to:

• Convert between different units of measurement
• Perform physics and engineering calculations
• Analyze dimensionality of physical quantities
• Work with SI, CGS, customary, and historical units
• Perform currency conversions
• Calculate with arbitrary precision

Installation

cargo install rink
rink --version

Also available via Homebrew: brew install rink

Core Usage

Interactive Mode

rink

Starts an interactive unit calculator session. Type expressions and press Enter to evaluate.

Evaluate Single Expression

rink "5 meters to feet"

Unit Conversions

Basic Conversions

# Length
5 meters to feet
1 mile to kilometers
100 centimeters to inches

# Mass
1 kg to pounds
500 grams to ounces

# Temperature
32°F to °C
100°C to °K

Velocity and Speed

# Speed conversions
100 km/h to mph
60 mph to m/s
speed of light to km/h

# Velocity
10 m/s to km/h

Energy and Power

# Energy
1 kWh to joules
1 calorie to joules
1 BTU to joules

# Power
100 watts to horsepower
1 horsepower to watts

Volume

1 gallon to liters
1 liter to cubic meters
1 cubic foot to gallons

Area

1 square meter to square feet
1 acre to square meters
1 hectare to acres

Physics Calculations

Force and Work

# Calculate force
10 kg * 9.8 m/s^2 to newtons

# Work and energy
50 newtons * 10 meters to joules

Electricity

# Power
120 volts * 2 amps to watts

# Energy consumption
100 watts * 5 hours to kWh

Mechanics

# Kinetic energy
0.5 * 10 kg * (10 m/s)^2 to joules

# Potential energy
10 kg * 9.8 m/s^2 * 5 meters to joules

Dimensionality Analysis

Unit Factorization

# Find units for a quantity
5 kg * m/s^2

# Rink will show this is equivalent to:
# 5 newton (force)

Physical Quantity Analysis

# Analyze dimensionality
joules / second

# Shows this is:
# watt (power)

Currency Conversions

# Currency conversion
100 USD to EUR
50 EUR to GBP
1000 JPY to USD

Advanced Features

Compound Calculations

# Complex expressions
(5 meters + 3 feet) to centimeters

# Multi-step calculations
10 kg * 9.8 m/s^2 * 5 meters to joules

Custom Units

# Define and use custom units
# (Rink has extensive built-in unit definitions)

Historical Units

# Historical measurements
1 rod to meters
1 furlong to kilometers
1 hogshead to liters

Examples

Electricity Cost Calculation

# Calculate annual electricity cost
# 100 watts for 4 hours/day at $0.1545/kWh
0.1545 $/kWh * 100 W * (4 hours / day) to $/year

Fuel Efficiency

# Convert fuel efficiency
9.4 km/l to mpg

# Historical units (rods per hogshead!)
9.4 km/l to rods per hogshead

Physics Problem

# Surface gravity of gold sphere the size of the moon
volume of moon * (19.283 g/cm^3) * G / (radius of moon)^2 to gravity

Unit Definitions

# Look up unit definitions
hogshead
liquidbarrel
rod

Supported Unit Systems

• SI (International System of Units)
• CGS (Centimeter-Gram-Second)
• Natural units
• International customary
• US customary
• UK customary
• Historical measurements

Tips

• Use to keyword for conversions
• Rink automatically handles unit factorization
• Shows SI physical quantities automatically
• Detailed error messages for invalid operations
• Helps with dimensionality analysis
• Arbitrary precision math for accurate calculations
• Web interface available at https://rinkcalc.app

Common Patterns

Distance and Speed

# Travel time calculation
100 km / (60 km/h) to hours

Energy and Cost

# Energy cost
1 kWh * 0.15 $/kWh to $

Area and Volume

# Tank volume
2 meters * 3 meters * 1.5 meters to liters

Scientific Notation

# Large numbers
1.23e6 meters to kilometers