Pint Units

Basic Usage

Creating Quantities

A quantity in Pint consists of a magnitude (number) and a unit.

from pint import UnitRegistry

# Create unit registry (do this once per module)
ureg = UnitRegistry()

# Define quantities with units
distance = 100 * ureg.meter
time = 5 * ureg.second
pressure = 50 * ureg.psi

# Alternative syntax using string parsing
flow_rate = ureg('250 gallons/minute')
temperature = ureg('75 degF')
viscosity = ureg('1.5 centipoise')

# Access magnitude and units
print(f"Distance magnitude: {distance.magnitude}")  # 100
print(f"Distance units: {distance.units}")  # meter

Unit Conversions

Convert between compatible units automatically:

# Length conversions
distance = 100 * ureg.meter
print(distance.to('feet'))  # 328.084 foot
print(distance.to('kilometer'))  # 0.1 kilometer

# Pressure conversions
pressure = 100 * ureg.psi
print(pressure.to('bar'))  # 6.895 bar
print(pressure.to('pascal'))  # 689475.7 pascal

# Flow rate conversions
flow = 500 * ureg.gallons / ureg.minute
print(flow.to('liter/second'))  # 31.546 liter/second
print(flow.to('m**3/hour'))  # 113.562 meter**3/hour

# Temperature conversions (handles offset units)
temp = 75 * ureg.degF
print(temp.to('degC'))  # 23.889 degree_Celsius
print(temp.to('kelvin'))  # 297.039 kelvin

Dimensional Analysis

Pint ensures dimensional consistency in calculations:

# Velocity = Distance / Time
distance = 100 * ureg.meter
time = 5 * ureg.second
velocity = distance / time
print(velocity)  # 20.0 meter/second

# Force = Mass × Acceleration
mass = 10 * ureg.kg
acceleration = 9.81 * ureg.meter / ureg.second**2
force = mass * acceleration
print(force)  # 98.1 kilogram·meter/second²
print(force.to('newton'))  # 98.1 newton

# Dimensional consistency check