Temperature systems at 1 atm

		Water
	Absolute Zero	Melting Point	Boiling Point
Fahrenheit	-459.67	32	212
Rankine	0	491.67	671.67
Reaumur	-218.52	0	80
Celsius	-273.15	0	100
Kelvin	0	273.15	373.15

Conversions

° F = (9/5)° C + 32

Rankine = ° F + 459.67

° C = (5/9)(° F - 32° )

K = ° C + 273.15°

Reaumur = (4/5)° C

Notes (including first year of usage)

Fahrenheit: 0° F is based on the temperature of a mixture of equal quantities by weight of snow and NaCl. 100° F is based on human body temperature. (1753)

Rankine: uses fahrenheit degree units, but sets zero equal to absolute zero. (1926)

Reaumur: 0° R based on freezing point of water and 80° R based on the boiling point. (1814)

Centigrade: 0° C based on freezing point of water and 100° C on the boiling point. (1801)

Celsius: Anders Celsius improved the Centigrade scale by defining 0.01° C as the triple point of water and 100° C as the boiling point. (1850)

Kelvin: uses celsius degree units but sets zero equal to absolute zero. (1908)

By Matthew Monroe in Chapel Hill, NC