## Kepware Knowledge Base: Solution

#### Temperature Scales and Conversion Formulas for Derived Tags

Last Update: 2018/11/12

Kelvin Scale
The Kelvin (K) is a unit increment of temperature, and is one of the seven SI base units. It is a thermodynamic (absolute) temperature scale where Absolute Zero (the theoretical absence of all thermal energy) is zero (0 K).

Celsius Scale

Celsius ( C) is a temperature scale named after the astronomer Anders Celsius (1701-1744), who developed a similar temperature scale two years before his death. It is also known as centigrade. A degree Celsius can refer to a specific temperature on the Celsius scale, and can also serve as a unit increment to indicate a temperature interval (which is a difference between two temperatures or an uncertainty).

Fahrenheit Scale

Fahrenheit ( F) is a temperature scale named after the physicist Daniel Gabriel Fahrenheit (1686-1736), who proposed it in 1724.

Rankine Scale

Rankine (R or Ra to distinguish it from the R mer and R aumur scales) is a temperature scale named after the physicist William John Macquorn Rankine (1820-1872), who proposed it in 1859. The Rankine scale is similar to the Kelvin scale in that zero is Absolute Zero; however, a degree Rankine is defined as equal to one degree Fahrenheit as opposed to one degree Celsius (as used by the Kelvin scale). A temperature of -459.67 F is equal to 0 R.

KelvinCelsiusFahrenheitRankine
Absolute Zero (by definition)0 K-273.15 C-459.67 F0 R
Freezing Point of Water 273.15 K0 C32 F491.67 R
Triple Point of Water [by definition]273.16 K0.01 C32.018 F491.688 R
Boiling Point of Water373.1339 K99.9839 C211.9710 F671.641 R

Conversion Formulas

• Celsius From Kelvin: [ C] = [K] - 273.15
• Kelvin from Celsius: [K] = [ C] + 273.15
• Fahrenheit from Kelvin: [ F] = [K] 9/5 - 459.67
• Kelvin from Fahrenheit: [K] = ([ F] + 459.67) 5/9
• Fahrenheit from Celsius: [F] = [C] 9/5 + 32
• Celsius from Fahrenheit: [C] = ([F] - 32) 5/9
• Rankine from Kelvin: [ R] = [K] 9/5
• Kelvin from Rankine: [K] = [ R] 5/9

Calculating Wind Chill
Wind Chill = 35.74 + 0.6215(T) - 35.75((V)^0.16) + 0.4275(T)((V)^0.16)

• T is the air temperature in degrees Fahrenheit ( F)
• V is the wind speed in Miles Per Hour (MPH)
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