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# Temperature

Temperature (sometimes called thermodynamic temperature) is a measure of the average kinetic energy of the particles in a system. Temperature is the degree of "hotness" ( or "coldness") - a measure of the heat intensity. The most common symbol or abbreviation for temperature is T.

When two objects of different temperatures are in contact - the warmer object becomes colder while the colder object becomes warmer. This means that heat flows from the warmer to the colder object.

### Temperature Converter

Convert between °C (Celsius), °F (Fahrenheit), K (Kelvin) and °R (Rankine) with the calculator below:

Temperature

°C

°F

K

°R

 Rankine Kelvin Fahrenheit Celsius °R K °F C 0 0 -459.67 -273.15 100 55.56 -359.67 -217.59 180 100 -279.67 -173.15 459.67 255.37 0 -17.78 491.67 273.15 32 0 559.67 310.93 100 37.78 671.67 373.15 212 100

### Temperature Converter - Web App

Add the Temperature Converter Web App to your mobile device or desktop. The App is saved in your browser and works offline automatically after first visit.

### Degree Celsius (°C) and Degree Fahrenheit (°F)

A thermometer can help us determine how cold or hot a substance is. Temperature is in most of the world measured and reported in degrees Celsius (°C). In the U.S. it is common to report temperature in degrees Fahrenheit (°F). In the Celsius and Fahrenheit scales the temperatures where ice melts (water freezes) and water boils are used as reference points.

• In the Celsius scale the freezing point of water is defined as °C and the boiling point is defined as 100 °C
• In the Fahrenheit scale the water freezes at 32 °F and boils at 212 °F

In the Celsius scale there are 100 degrees between the freezing point and the boiling point of water compared to 180 degrees in the Fahrenheit scale. This means that °C = 1.8 °F (check the section about temperature differences below).

Values can be converted between the two temperature units by using the equations:

T(°F) = 1.8 T(°C) + 32                           (1)

T(°C) = (T(°F) - 32)/1.8                         (2)

where

T(°C)= temperature (°C )

T(°F)= temperature (°F)

### Celsius vs. Fahrenheit

Temperature
oCoF
-20 -4
-15 5
-10 14
-5 23
0 32
5 41
10 50
15 59
20 68
25 77
30 86
35 95
40 104
45 113
50 122

Example: A patient with SARS (Severe Acute Respiratory Syndrome) has a temperature of 106 °F. What is the temperature in Celsius?

T(°C) = (106 °F - 32)/1.8   = 41.1 °C

### Temperature Difference - or Temperature Change - degree Celsius versus degree Fahrenheit

Note that for temperature difference (change) - as used in heat loss diagrams

• 1 degree Celsius of temperature difference equals 1.8 degree Fahrenheit of temperature difference

ΔT(°C) = ΔT(°F) / 1.8                            (3)

ΔT(°F) = 1.8 ΔT(°C)                            (4)

where

ΔT(°F) = temperature difference (°F)

ΔT(°C) = temperature difference (°C)

Example: Water is cooled from 100°C to 60°C. What is the temperature difference in °F?

Temperature difference in degrees Celsius:

ΔT(°C) = 100 °C - 60 °C = 40 C°

Note that °C is used for actual temperatures (temperature relative to 273.15 K) and C° is used for temperature differences.

Temperature difference in degrees Fahrenheit calculated by using (1)

100 °C = 1.8 (100 °C) + 32 = 212 °F

60 °C = 1.8 (60 °C) + 32 = 140 °F

ΔT(°F) =  212°F140°F = 72 °F

Temperature difference in degrees Fahrenheit calculated by using (3)

ΔT(°F) = 1.8 (40 C°) = 72 °F

#### Temperature Difference Converter

Temperature Difference

°F

### Kelvin - K

Another scale (common in science) is Kelvin, or the Absolute Temperature Scale. On the Kelvin scale the coldest temperature possible, -273 °C, has a value of 0 Kelvin (0 K) and is called the absolute zero. Units on the Kelvin scale are called Kelvins (K) and no degree symbol is used.
Because there are no lower temperatures than 0 K  - the Kelvin scale does not have negative numbers.

The Kelvin has the same incremental scale as the Celsius scale and one unit Kelvin is equal in size to one unit Celsius:

1 unit Kelvin  = 1 unit °C

ΔT(°K) = ΔT(°C)                                (5)

To calculate a Kelvin temperature, add 273 to the Celsius temperature:

T(K) = T(°C) + 273.15                        (6)

Example: What is the normal body temperature of 37 oC in the Kelvin scale?

T(K) = T(°C) + 273.15 = 37°C + 273.15 = 310.15 K

### Degree Rankine - R

In the English system the absolute temperature is in degrees Rankine (R), not in Fahrenheit:

T(°R) = 1.8*T(K)                                 (7)

T(°R) = 1.8*(T(°C)+273.15)

T(°R) = T(°F) + 459.67                      (8)

ΔT(°R) = ΔT(°F)                                (9)

## Related Topics

### • Basics

The SI-system, unit converters, physical constants, drawing scales and more.

### • Temperature Measurement

Measurment of temperature - probes, sensors and transmitters.

### • Thermodynamics

Work, heat and energy systems.

## Related Documents

### Ammonia - Properties at Gas-Liquid Equilibrium Conditions

Figures and tables showing how the properties of liquid and gaseous ammonia changes along the boiling/condensation curve (temperature and pressure between triple point and critical point conditions). An ammonia phase diagram are included.

### Arithmetic and Logarithmic Mean Temperature Difference

Arithmetic Mean Temperature Difference in Heat Exchangers - AMTD - and Logarithmic Mean Temperature Difference - LMTD - formulas with examples - Online Mean Temperature Calculator.

### Fixed Temperature Points

Temperature points that can be used as a reference for calibration

### Globe Temperature

The resultant or globe temperature.

### Hydrocarbon Mixtures - Average Boiling Points vs. Gravity and Molecular Weights

Formulas and examples of calculation of boiling point of hydrocarbon mixtures from gravity and molecular weight.

### Hydrocarbon Mixtures - Molecular Weight vs. Gravity and Average Boiling Point

Formulas and examples of calculation of average molecular weight of hydrocarbon mixtures from gravity and average boiling point, achieved from distillation data.

### International Standard Atmosphere

International standard atmosphere in elevation -2000 to 30000 metre - pressure, temperature, density, viscosity, thermal conductivity and velocity of sound.

### Liquids and Gases - Boiling Points

Boiling temperatures for common liquids and gases - acetone, butane, propane and more.

### Metals, Metallic Elements and Alloys - Thermal Conductivities

Thermal conductivities of common metals, metallic elements aand alloys.

### Non-ideal gas - Van der Waal's Equation and Constants

The van der Waals constants for more than 200 gases used to correct for non-ideal behavior of gases caused by intermolecular forces and the volume occupied by the gas particles.

### Pt100 Platinum Resistance Thermometer

Pt100 electrical resistance temperature sensor - ranging -220 to 750 degrees Celsius.

### Rankine Efficiency

The efficiency of the Rankine cycle.

### RTD Resistance Temperature Sensor

Thermal resistive sensor - a basic introduction.

### Survival Time in Cold Water

Time to exhaustion and death for humans in cold water.

### The Ideal Gas Law

The relationship between volume, pressure, temperature and quantity of a gas, including definition of gas density.

### Thermocouples

Thermocouples - types, principles and temperature ranges.

### Universal and Individual Gas Constants

The Universal and Individual Gas Constants in fluid mechanics and thermodynamics. Individual gas constants for the most common gases.

### Water - Properties at Gas-Liquid Equilibrium Conditions

Figures and tables showing how the properties of water changes along the boiling/condensation curve (vapor pressure, density, viscosity, thermal conductivity, specific heat, Prandtl number, thermal diffusivity, entropy and enthalpy).

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