Learn about Celsius. Understand what Celsius or centigrade is, its unit, how to convert other temperature units to Celsius, and see examples of the conversion.
Updated: 11/21/2023
Celsius Overview, Conversion & Examples
Table of Contents
- What Is Celsius?
- Temperature Conversions: Celsius, Kelvin, and Fahrenheit
- Examples of Temperature Conversions
- Lesson Summary
Frequently Asked Questions
What is Celsius temperature scale?
The Celsius temperature scale, also called the centigrade scale, is a scale that sets the freezing point of water at 0°C and the boiling point of water at 100°C.
How do you use Celsius?
The Celsius scale is used in much of the world for everyday temperatures. It is also the standard unit of temperature in science.
What is difference between Celsius and Fahrenheit?
The Celsius scale is a centigrade scale with the freezing point of water set to 0°C and the boing point set to 100°C. The Fahrenheit scale is not a centigrade scale and has the freezing point of water set to 32°F and the boiling point set to 212°F.
Table of Contents
- What Is Celsius?
- Temperature Conversions: Celsius, Kelvin, and Fahrenheit
- Examples of Temperature Conversions
- Lesson Summary
The Celsius scale is the most widely used metric by which temperature is measured. In addition to being utilized in countries that use the metric system, the Celsius scale is also the standard way to measure temperature in science. The units that make up the Celsius scale are degrees Celsius, written as o C. For example, the temperature 23 degrees Celsius would be written as 23o C.
Centigrade
Anders Celsius, a Swedish astronomer, invented the early version of this temperature scale in 1742. Interestingly, the scale he invented was an inverted version of what the Celsius scale is today. He had defined the boiling point to be 0o C and the freezing point to be 100o C. His scale was a centigrade scale, which is any scale that has 100 units between the two defining points. The Celsius scale is also referred to as the centigrade scale.
 |
The centigrade scale that was invented by Celsius has withstood the test of time, albeit with a few modifications. First, and most obviously, the scale was flipped such that the freezing point is the low temperature, and the boiling point is the high temperature. Second, the name was changed to honor Celsius after his death. Although the name of the scale was changed to Celsius in the 18th century, the units of the scale were referred to as degrees centigrade until the mid-20th century. This means that until recently, 20o C was read as 20 degrees centigrade.
Common Temperatures
In addition to the boiling and freezing point of water, this table highlights some of the other common temperatures in Celsius.
| Temperature | |
|---|---|
| Absolute Zero | -273.15o C |
| Freezing Point of Water | 0o C |
| Room Temperature | 20o C |
| Human Body Temperature | 37o C |
| Boiling Point of Water | 100o C |
To unlock this lesson you must be a Study.com Member.
Create your account
You must cCreate an account to continue watching
Register to view this lesson
Are you a student or a teacher?
Create Your Account To Continue Watching
As a member, you'll also get unlimited access to over 88,000 lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed.
Get unlimited access to over 88,000 lessons.
Try it now
It only takes a few minutes to setup and you can cancel any time.
Already registered? Log in here for access
BackResources created by teachers for teachers
Over 30,000 video lessons
& teaching resources‐all
in one place.
I would definitely recommend Study.com to my colleagues. It’s like a teacher waved a magic wand and did the work for me. I feel like it’s a lifeline.
Jennifer B.
Teacher
Back
Your next lesson will play in
10 seconds
As alluded to earlier, the Celsius scale is not the only temperature scale in use. The Fahrenheit and Kelvin scales are two other scales that are both popular in their own context.
Kelvin Scale
The Kelvin scale was developed in 1848 by William Thomson, better known as Lord Kelvin. The Kelvin scale was modeled after the Celsius scale in that there are 100 units between the freezing and boiling points of water. Units on this scale are referred to as kelvins and abbreviated as K. Lord Kelvin designed this scale so that 0o K was absolute zero. Absolute zero is the temperature at which particle motion is minimal and the system has the lowest amount of energy possible. So, not only is the Kelvin scale a centigrade scale, but it is also an absolute scale.
The kelvin is also the International System of Units (SI) for thermodynamic temperature. Originally, the kelvin was defined in relation to the triple point of water, or the point at which solid, liquid and gaseous water exist in equilibrium. Today, it is defined in relation to the Boltzmann constant, which relates the kinetic energy of gas particles with the temperature of the system. The Boltzmann constant is defined as 1.380649 x 10-23 Joules/kelvin. As a result of this, the kelvin is primarily used in the physical sciences.
Fahrenheit Scale
The Fahrenheit temperature scale is used primarily in the United States and its territories. It is also used in the Cayman Islands and Liberia. Outside of these countries, the Fahrenheit scale is rarely used. Although everyday temperatures are given in degrees Fahrenheit, scientists in these countries use degrees Celsius or kelvin in their work. As with the other scales, the units on the Fahrenheit scale are degrees Fahrenheit, abbreviated as o F.
In 1724, Gabriel Fahrenheit developed an early version of the temperature scale that bears his name. He started by setting 0o F to be the temperature at which an ice-salt mixture exists in equilibrium. The other limit was set at 90o F, which was his best estimate of human body temperature. At some point, he noted that around 30o F was the temperature of ice water. These were later adjusted to 98.6o F and 32o F, respectively. Unlike the Celsius and Kelvin scales, the Fahrenheit scale has 180 degrees between the freezing and boiling points of water. Thus, the Fahrenheit scale is not a centigrade scale.
 |
Despite the differences between the scales, the conversion from one scale to another is straightforward. As such, it is easy to convert a temperature from an unfamiliar scale to one that is more familiar.
Kelvin to Celsius Conversion
Conversions between the two centigrade scales are simple.
To convert from Kelvin to Celsius, the following equation is used:
oIn the equation, K is the temperature in Kelvin and C is the temperature in Celsius. 273.15 is the freezing point of water on the Kelvin scale.
To convert from Celsius to Kelvin, the following equation is used:
K = o C + 273.15
Fahrenheit to Celsius Conversions
Converting between Fahrenheit and Celsius is a little more complicated due to the fact that the Fahrenheit scale has a 180-degree spread between the freezing and boiling points and the Celsius scale just has a 100-degree spread.
To convert from Fahrenheit to Celsius, the following equation is used:
ooIn the equation, F is the temperature in Fahrenheit and C is the temperature in Celsius. The 5/9 fraction is used to correct for the difference in the spread, and 32 is the freezing point of water on the Fahrenheit scale.
To convert from Celsius to Fahrenheit, the following equation is used:
oo
To unlock this lesson you must be a Study.com Member.
Create your account
Here are a couple of examples to illustrate how to use the equations:
Example 1
The temperature in Omaha, Nebraska is 27o F. What is the temperature in Celsius?
This problem asks to convert from Fahrenheit to Celsius.
The best equation to use is o C = 5/9( o F - 32)
Substitute the 27o F in order to get o C = 5/9(27) - 32)
Next, simplify to get the answer o C = -17, or -17o C.
Example 2
A thermometer reads 95o C. What is the temperature in Fahrenheit? What is the temperature in Kelvin?
This problem asks you to convert from Celsius to Fahrenheit.
The best equation to use is o F = (9/5)( o C) + 32
Substitute the 95o C in to get o F = (9/5)(95) + 32
Next, simplify to get the answer o F = 203 , or 203o F.
Example 3
A thermometer reads 95o C. What is the temperature in Kelvin?
This problem asks you to convert from Celsius to Kelvin.
The best equation to use is K = o C + 273.15
Substitute the 95o C in to get K = (95) + 273.15
Next, simplify to get the answer K = 368.15, or 368.15K.
To unlock this lesson you must be a Study.com Member.
Create your account
The Celsius scale was invented by Anders Celsius in 1742. The units of this scale are degrees Celsius, abbreviated as o C. The Celsius scale is a centigrade scale because there are 100 units between the freezing (0o C) and boiling points (100o C) of water. This temperature scale is used in most of the world and is the accepted unit of measurement in science.
The Kelvin scale and the Fahrenheit scale are two other temperature scales commonly used. The Kelvin scale is used in the physical sciences. Its unit is the kelvin, K, which is also the base unit of thermodynamic temperature. To go from Kelvin to Celsius or vice versa, use the equations o C = K - 273.15 and K = o C + 273.15, respectively. The Fahrenheit scale is predominately used in the United States, the Cayman Islands, and Liberia. Degrees Fahrenheit, abbreviated as o F, are the units of the scale. To go from Fahrenheit to Celsius or vice versa, use the equations o C = 5/9( o F - 32) and o F = (9/5)( o C) + 32, respectively.
To unlock this lesson you must be a Study.com Member.
Create your account
Video Transcript
Definition of Celsius
In science, the Celsius scale is used more often than the Fahrenheit scale. The Celsius scale is divided into 100 equal parts, called degrees Celsius (°C), between the freezing point and boiling point of water. This scale was invented by Anders Celsius in 1742. Celsius also based his scale on the freezing and boiling points of water. The freezing point of water on this scale is 0 degrees Celsius (0°C). The boiling point of water is 100 degrees Celsius (100°C). This thermometer scale is sometimes called the centigrade scale because there are 100 Celsius degrees between the two fixed points.
Temperature Conversions
As shown by these thermometers, a given temperature is represented by different numbers on the three temperature scales:
 |
For example, the freezing point of water is 32°F, 0°C, or 273 degrees Kelvin. As you can see, 0°C is actually a much higher temperature than 0 K, but a change of 1 degree Kelvin is equal to a change of one Celsius degree. In addition, 0°C is a higher temperature than 0°F, but a change of one Fahrenheit degree is not equal to a change of one Celsius degree. We can convert from one scale to another using these simple equations.
 |
Let's look at some examples on how to use the conversion table. A weather report of 21°C in London, England, predicts a pleasant day, good for shorts and a T-shirt. A weather report of 21°F in Minneapolis, Minnesota, means a heavy winter coat, gloves, and a hat will be needed. Because the U.S. is only one of a few countries that use the Fahrenheit scale, it is useful to know how to convert between Fahrenheit and Celsius.
- T(Fahrenheit) = 9/5 T(Celsius) + 32
- T(Celsius) = 5/9( T(Fahrenheit) - 32)
 |
Fahrenheit to Celsius Conversions
Let's look at the examples of major conversions between various temperature scales.
A friend in Paris sends you a recipe for a cake. The French recipe says to bake the cake at a temperature of 200°C for 45 minutes. At what temperature should you set your oven, which uses the Fahrenheit scale?
Let's break this question down.
1. You're looking for: the temperature in degrees Fahrenheit
2. You're given: the temperature in degrees Celsius
3. Relationships: Use the conversion formula: T(F) = 9/5 T(C) + 32
4. Solution: T(F) = (9/5)(200) + 32 = 392°F
The scale that is still used in modern scientific work (although it is gradually being replaced) is associated with the name of a man who neither first proposed it nor ever actually produced it. Anders Celsius (1742) used the freezing and boiling point of water for reference points and then divided the distance between them into 100 equal parts: a convenient scheme for the user. Strangely enough, Celsius set the temperature of freezing water at 100° and boiling at 0°. Some years later, with these two numbers more reasonably interchanged, the arrangement came to be known as the centigrade scale (from the Latin centum, meaning 100, and gradus, meaning degree). The tenth International Conference on Weights and Measures (in 1954) changed the scale's name to the Celsius scale.
 |
Let's solve more problems on conversions between Celsius and Fahrenheit temperature scales.
Let's say you are planning a trip to Iceland where the average July temperature is 11.2°C. What is the temperature in Fahrenheit?
1. You're looking for: the temperature in degrees Fahrenheit
2. You're given: the temperature in degrees Celsius.
3. Relationships: Use the conversion formula: T(F) = 9/5 T(C) + 32
4. Solution: T(F) = (9/5)(11.2) + 32 = 52.2°F
Here's another example: you are doing a science experiment with a Fahrenheit thermometer. Your data must be in degrees Celsius. If you measure a temperature of 125°F, what is this temperature in degrees Celsius?
1. You're looking for: the temperature in degrees Celsius
2. You're given: the temperature in degrees Fahrenheit
3. Relationships: Use the conversion formula: T(C) = 5/9(T(F) - 32)
4. Solution: T(C) = (5/9)(125 - 32) = 51.7°C
Here's a final, two-part example. The temperature on the Moon varies from -230°C at night to 120°C during the day. What is the range in temperature on the Moon in degrees Fahrenheit?
First, you will have to convert -230°C into degrees Fahrenheit:
1. You're looking for: the temperature in degrees Fahrenheit
2. You're given: the temperature in degrees Celsius
3. Relationships: Use the conversion formula: T(F) = 9/5 T(C) + 32
4. Solution: T(F) = (9/5)(-230) + 32 = -382°F
Second, you will have to convert 120°C into degrees Fahrenheit:
1. You're looking for: the temperature in degrees Fahrenheit
2. You're given: the temperature in degrees Celsius
3. Relationships: Use the conversion formula: T(F) = 9/5 T(C) + 32
4. Solution: T(F) = (9/5)(120) + 32 = 248°F
Answer: the range in temperature on the Moon is from -382°F to 248°F.
Kelvin to Celsius Conversion
Now, let's do some conversions between Kelvin and Celsius temperature scales.
The Kelvin (K) unit of temperature is the same size as the Celsius degree. However, water freezes at 273 K and boils at 373 K.
The relationships used for conversions between Kelvin and Celsius temperature scales are as follows:
T(C) = T(K) - 273
T(K) = T(C) + 273
Most of the outer planets and moons have temperatures closer to absolute zero than to the freezing point of water. (The average surface temperature of Saturn's largest moon Titan is 93 K.) To convert from Celsius to Kelvin, you add 273 to the temperature in Celsius. For example, a temperature of 21°C is equal to T(K) = T(C) + 273, which is 294 K (or 21+273).
Lesson Summary
The Celsius temperature scale is typically used in International System of Units (SI) and in science. To convert between Celsius and Fahrenheit temperature systems, use the equations: T(F) = 9/5 T(C) + 32 or T(C) = 5/9(T(F) -32). To convert between Kelvin and Celsius temperature systems, use T(C) = T(K) - 273 or T(K) = T(C) + 273.
Learning Outcomes
After you've completed this lesson, you'll be able to:
- Describe the history of the Celsius scale and how it is used today
- Compare and contrast the Celsius, Fahrenheit and Kelvin scales
- Explain how to convert between Celsius and Fahrenheit and between Celsius and Kelvin
To unlock this lesson you must be a Study.com Member.
Create your account
Register to view this lesson
Are you a student or a teacher?
Unlock Your Education
See for yourself why 30 million people use Study.com
Become a Study.com member and start learning now.
Become a MemberAlready a member? Log In
BackResources created by teachers for teachers
Over 30,000 video lessons
& teaching resources‐all
in one place.
I would definitely recommend Study.com to my colleagues. It’s like a teacher waved a magic wand and did the work for me. I feel like it’s a lifeline.
Jennifer B.
Teacher
Back
Celsius Overview, Conversion & Examples
Related Study Materials
Explore our library of over 88,000 lessons
Browse by subject