# Fahrenheit

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Conversion Formulae

The conversion formula for obtaining degrees fahrenheit (°F) from degrees rankine (°R) is as follows:

• °F = °R - 459.67

The conversion formula for obtaining degrees rankine (°R) from degrees fahrenheit (°F) is as follows:

• °R = °F + 459.67

The Rankine temperature scale was created in response to the need for an absolute thermometric scale, it has its zero point at absolute zero and progresses from that point.

The Rankine scale has the same interval as the fahrenheit scale, thus a change of 1 degree rankine is the same as that of 1 degree fahrenheit.

Fahrenheit

The Fahrenheit temperature scale is a non SI temperature scale that is now based on two fixed points, the freezing point of water at 32 °F and the boiling point of water 100 °F.

US Customary

### Definition

1 degree fahrenheit is 1/180th of the interval between the freezing point and boiling point of water. The scale is defined by the freezing point of water at 32 °F and the boiling point of water at 212 °F.

### Base Unit

Fahrenheit

The fahrenheit temperature scale is used in US Customary units and was formerly used in British Imperial units as the main unit of temperature.

Formal: °F

### Information

The Fahrenheit temperature scale is names after Daniel Fahrenheit, inventor of the mercury thermomenter, who first proposed the scale in 1724.

Fahrenheit's original scale wasn't based around the freezing and boiling points of water. Some stories say it was based on the lowest temperature to which Farhenheit could reproducibly cool brine (0 degrees) and the average human body temperature (100 degrees), though these would appear to be strange reference points and given that serious research on average human body temperature wasn't done until the 19th century fairly unlikely to be true.

Other sources link the work of Fahrenheit to earlier work done by Ole Rømer, whose temperature scale was based on the freezing point of brine and the boiling point of water.

The Fahrenheit temperature scale was used widely around the world until the mid to late 20th Century when many countries that had previously used Fahrenheit, such as the United Kingdom, Canada, India and Australia, adopted the SI metric Celsius temperature scale.

Fahrenheit is used in the United States of America, the Bahamas, Belize, the Cayman Islands and US Territories such as Guam, Puerto Rico and the US Virgin Islands.

### Conversion Formulae For Conversion To Fahrenheit

• °F = (°C x 9/5) + 32
• 32 °F = 0 °C
• 212 °F = 100 °C

• °F = (K x 9/5) - 459.67
• 32 °F = 273.15 K
• 212 °F = 373.15 K

• °F = °R - 459.67
• 32 °F = 491.67 °R
• 212 °F = 671.67 °R

### Conversion Formulae For Conversion From Fahrenheit

• °C = (°F - 32) x 5/9
• K = (°F + 459.67) x 5/9
• °R = °F + 459.67
Rankine

The Rankine temperature scale is a temperature scale with zero at absolute zero, with the degree Rankine being equivalent to degree Fahrenheit. Effectively Rankine is to Fahrenheit as Kelvin is to Celsius.

None

### Definition

The Rankine temperature scale is defined as having zero at absolute zero and having the degree Rankine equivalent to the degree Fahrenheit.

### Base Unit

Degree Rankine

The degree Rankine is, however, equivalent to the degree Fahrenheit.

### Abbreviation

Formal: °R

°Ra and R are also sometimes used, the first to differentiate it from other archaic temperature scales and the latter to be in line with the use of K for kelvin.

### Information

The Rankine temperature scale is named after William Macquorn Rankine, a Scottish engineer and physicist, who proposed the scale in 1859.

The Rankine temperature scale may still be in use in some engineering disciplines in the United States of America and its territories such as Guam and the US Virgin Islands. Its use is now not recommended by the US National Institute of Standards and Technology (NIST) and is being superseded by use of the Kelvin scale.

### Conversion Formulae For Conversion To Rankine

• °R = K x 9/5
• 0 °R = 0 K

• °R = °F + 459.67
• 0 °R = -459.67 °F

• °R = (°C + 273.15) x 9/5
• 0 °R = -273.15 °C

### Conversion Formulae For Conversion From Rankine

• K = °R x 5/9
• °F = °R - 459.67
• °C = (°R - 491.67) x 5/9
Common Conversions °C to K
 °F °R 32 491.67 42 501.67 52 511.67 62 521.67 72 531.67 82 541.67 92 551.67 102 561.67 112 571.67 122 581.67
 °F °R 132 591.67 142 601.67 152 611.67 162 621.67 172 631.67 182 641.67 192 651.67 202 661.67
Common Conversions K to °C
 °R °F 0 -459.67 100 -359.67 200 -259.67 300 -159.67 400 -59.67 500 40.33 600 140.33 700 240.33 800 340.33 900 440.33