SciPy Constants

Mathematical and Physical Constants

scipy.constants bundles a large set of mathematical and physical constants as plain Python floats, based on the CODATA recommended values used across science and engineering. Rather than typing 3.14159... or looking up the speed of light, you import the constant by name.

from scipy import constants

print(constants.pi)                      # 3.141592653589793
print(constants.speed_of_light)          # 299792458.0 (meters/second)
print(constants.Avogadro)                # 6.02214076e+23
print(constants.gravitational_constant)  # 6.6743e-11

Unit Conversion Constants

Beyond fixed values like pi, scipy.constants also stores unit-conversion factors. Each one tells you how many SI base units make up one unit of something else - for example, constants.mile is the number of meters in a mile, a plain float you multiply by rather than a formula.

from scipy import constants

print(constants.mile)    # 1609.344 (meters in one mile)
print(constants.inch)    # 0.0254 (meters in one inch)
print(constants.minute)  # 60.0 (seconds in one minute)

# Convert 5 miles to meters
distance_in_meters = 5 * constants.mile
print(distance_in_meters)  # 8046.72

from scipy import constants

# Search physical_constants for anything mentioning 'electron mass'
matches = constants.find('electron mass')
print(matches[0])  # 'electron mass'

• Length and distance - constants.mile, constants.inch, constants.foot
• Mass - constants.gram, constants.pound, constants.ounce
• Time - constants.minute, constants.hour, constants.day
• Temperature - constants.zero_Celsius, constants.degree