Fahrenheit to Kelvin Conversion: Definition, Facts, Examples, FAQs

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What Is the Fahrenheit to Kelvin Conversion?

Fahrenheit to Kelvin conversion is used to convert a given temperature measured in Fahrenheit scale into the Kelvin scale.

Fahrenheit to Kelvin Formula (F to K formula): $T_{K} = (T_{F} + 459.67) \times \frac{5}{9}$

Temperature is the measurement of how hot or cold a body or an environment or an object is. It can be measured in Fahrenheit (° F) scale, Celsius (°C) scale, or Kelvin (K) scale.

The Fahrenheit scale is normally used in the United States, while the Celsius scale is used worldwide. The Kelvin scale is used extensively for scientific calculations.

What Is the Fahrenheit Scale of Temperature?

The Fahrenheit scale is named after a German scientist Daniel Fahrenheit, the inventor of the mercury thermometer, in 1724.

• The freezing point of water in the Fahrenheit scale = 32 °F.
• The boiling point of water in the Fahrenheit scale = 212 °F.

The boiling point (steam point) and the freezing point (the ice point) of water are separated by exactly 180 equal divisions. Each division is one degree Fahrenheit, denoted by °F.

What Is the Kelvin Scale of Temperature?

The Kelvin scale was first proposed by Scottish Lord Kelvin as a scientific scale based on the concept of absolute zero. Absolute zero is the temperature at which all movement in matter would stop or freeze (0 K = −273.15 °C = −459.67 °F).

Kelvin is the base unit of temperature in the international system of units. This scale has no negative values. In the Kelvin’s scale, the zero point is 273.15 below that of the Celsius scale (0 K = -273.15 °C).

• Freezing point of water in the Kelvin scale = 273.15 K.
• Boiling point of water in the Kelvin scale = 373 K

Unlike the Celsius and Fahrenheit scale, the temperature in Kelvin is not accompanied by the word “degree.” One should say 250 Kelvin and not 250 degree Kelvin.

Fahrenheit to Kelvin Conversion

There are two ways that you can convert Fahrenheit to Kelvin, either converting directly to Kelvin, or converting to Celsius and then converting that measurement to Kelvin.

Fahrenheit to Kelvin Conversion – Direct Method

To convert temperature in Fahrenheit to Kelvin, you can use this formula for Fahrenheit to Kelvin conversion:

$T_{K} = (T_{F} + 459.67) \times \frac{5}{9}$

where

$T_{K}$: Temperature in Kelvin

$T_{F}$: Temperature in Fahrenheit

Example: Convert 90°F to Kelvin.

$T_{K} = (90 + 459.67) \times \frac{5}{9}$

$T_{K} = 305.37 K$

“Fahrenheit to Celsius” followed by “Celsius to Kelvin”

Convert Fahrenheit to Celsius to Kelvin (F to C to K) using the formulas:

• $°C = \frac{(°F \;−\; 32) \times 5}{9}$
• Kelvin = Celsius + 273.15

Step 1: Subtract 32 from the Fahrenheit temperature.

Step 2: Multiply the result by 5.

Step 3: Divide this number by 9.

Step 4: Add 273.15 to this number.

Example: Convert 60 degrees Fahrenheit to Kelvin.

Step 1: Subtract 32 from 60°F.

60 – 32 = 28

Step 2: Multiply the result 28 by 5.

28 $\times$ 5 = 140

Step 3: Divide 140 by 9.

140 ÷ 9 = 15.56

Step 4: Add 273.15 to 15.56.

273.15 + 15.56 = 288.71

Thus, 60⁰ F = 288.71 K

Fahrenheit to Kelvin Conversion Table

Fahrenheit and Kelvin scales read the same temperature at 574.25.

Facts about Fahrenheit to Kelvin Formula

• The S.I. unit of temperature is Kelvin. The lowest possible temperature on the Kelvin scale is absolute zero. Absolute zero is the lowest temperature any substance can drop down to.
• Fahrenheit is a degree scale. The Fahrenheit scale is made of smaller units where a one-degree change on the Kelvin scale is equal to 1.8°F change on the Fahrenheit scale. The degree symbol is not used to report temperature using the Kelvin scale.
• Boiling point of water = 100 °C = 212 °F = 373.15 K
Freezing point of water = 0 °C = 32 °F = 273.15 K
• Kelvin to Fahrenheit Conversion Formula:
$T_{F} = (T_{K} \times \frac{9}{5})\;-\;459.67$
• Fahrenheit to Celsius Formula:
$°C = \frac{5}{9} \times (°F \;-\; 32)$

Conclusion

In this article, we learned that we can change the temperature given in Fahrenheit to Kelvin and vice versa, by using the conversion formula. Let’s solve a few examples and practice some problems for better understanding.

Solved Examples onFahrenheit to Kelvin Formula

1. Convert 100 °F into Kelvin.

Solution:
$T_{F} = 100 ºF$
Using F to K formula,
$T_{K} = (T_{F} + 459.67) \times \frac{5}{9}$
Putting the value of temperature in F
$T_{K} = (100 + 459.67) \times \frac{5}{9}$
$T_{K} = (559.67) \times \frac{5}{9}$
$T_{K} = 310.93$ K
Therefore, 120 °F = 310.93 K.

2. Convert -40 °F into Kelvin.

Solution:
$T_{F} = \;-\;40 ºF$
Using F to K formula,
$T_{K} = (T_{F} + 459.67)\times \frac{5}{9}$
Putting the value of temperature in F
$T_{K} = (\;-\;40 + 459.67) \times \frac{5}{9}$
$T_{K} = (419.67) \times \frac{5}{9}$
$T_{K} = 2098.35\times \frac{1}{9}$
$T_{K} = 233.15$ K
Therefore, -40 °F = 233.15 K.

3. Convert 32 °F into Kelvin.

Solution:
$T_{F} = 32º$
Using F to K formula,
$T_{K} = (T_{F} + 459.67) \times \frac{5}{9}$
Putting the value of temperature in F
$T_{K} = (32 + 459.67) \times \frac{5}{9}$
$T_{K} = (491.67) \times \frac{5}{9}$
$T_{K} = 273.15$ K
Therefore, 32 °F = 273.15 K.

4. Convert 98.6 °F into Celsius and then to Kelvin.

Solution:

$T_{F} = 98.6 ºF$
We will use the following formulas.

• F to C formula: $°C = \frac{(°F − 32) \times 5}{9}$
• Celsius to Kelvin Formula: Kelvin = Celsius + 273.15

$°C = \frac{(°F − 32) \times 5}{9} = \frac{(98.6 − 32) \times 5}{9} = \frac{(66.6) \times 5}{9} = 37$

Kelvin = Celsius + 273.15 = 37 + 273.15 = 310.15 K

Practice Problems on Fahrenheit to Kelvin Conversion

1

What is the value of 0 °F in Kelvin?

267.37 K
255.37 K
305.27 K
312.27 K
CorrectIncorrect
We use the formula of Fahrenheit to Kelvin
Using F to K formula,
$T_{K} = (T_{F} + 459.67) \times \frac{5}{9}$
Putting the value of temperature in F
$T_{K} = (0 + 459.67) \times \frac{5}{9} = 459.67 \times \frac{5}{9} = 255.37$ K
2

What is the value of 1 Kelvin in Fahrenheit?

357.87
457.87
-357.87
-457.87
CorrectIncorrect
The formula for Kelvin to Fahrenheit conversion is
$T_{F} = (T_{K} \times \frac{9}{5})\;-\;459.67$
Putting the value of temperature in Kelvin
$T_{F} = (1\times\frac{9}{5})\;-\;459.67 = \frac{9}{5}\;-\; 459.67 = \;-\;457.87 °F$
3

Convert the temperature 68 °F in Kelvin.

273.15 K
293.15 K
477.15 K
497.15 K
CorrectIncorrect
Using F to K formula, we get
$T_{K} = (T_{F} + 459.67) \times \frac{5}{9}$
Putting the value of temperature in F
$T_{K} = (68 + 459.67) \times \frac{5}{9}$
$T_{K} = (527.67) \times \frac{5}{9}$
$T_{K} = 293.15$ K
4

What is the value of 100 Kelvin in Fahrenheit?

-279.67
-293.15
279.67
293.15
CorrectIncorrect
We use the formula for Kelvin to Fahrenheit
$T_{F} = (T_{K} \times \frac{9}{5})\;-\;459.67$
Putting the value of temperature in Kelvin
$T_{F} = (100 \times \frac{9}{5})\;-\;459.67 = 180 \;-\; 459.67 = \;-\;279.67 °F$

The simple formula for the conversion of Fahrenheit to Kelvin in math is

$K = \frac{F + 459.67}{1.8}$

Formula for conversion of Kelvin to Fahrenheit is given by

$F = (K \times 1.8) \;-\; 459.67$

From F to K, 1 Kelvin is equal to $\;-\;457.87$ Fahrenheit (ca. 237 degrees Celsius).

For every 1 K, Fahrenheit changes by 1.8 °F. So, the ratio of Fahrenheit to Kelvin is  1K:1.8 °F. The conversion from Kelvin to Fahrenheit involves multiplying by 1.8 and then adding 32.

Fahrenheit and Kelvin scales give the same reading at 574.59.

574.59 K = 574.59 °F.