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Thermometer (Gary S Chapman, Getty Images)Depending on how old you are, you might read 38°C as 38 degrees Celsius or 38 degrees centigrade. Why are there two names for °C and what's the difference? Here's the answer:

Celsius and centigrade are two names for essentially the same temperature scale (with slight differences). The centigrade scale is divided into degrees based on dividing the temperature between which water freezes and boils into 100 equal gradients or degrees. The word centigrade comes from "centi-" for 100 and "grade" for gradients. The centigrade scale was introduced in 1744 and remained the primary scale of temperature until 1948. In 1948 the CGPM (Conference General des Poids et Measures) decided to standardize several units of measurement, including the temperature scale. Since the "grade" was in use as a unit (including the "centigrade"), a new name was chosen for the temperature scale: Celsius.

The Celsius scale remains a centigrade scale in which there are 100 degrees from the freezing point (0°C) and boiling point (100°C) of water, though the size of the degree has been more precisely defined. A degree Celsius (or a Kelvin) is what you get when divide the thermodynamic range between absolute zero and the triple point of a specific type of water into 273.16 equal parts. There is a 0.01°C difference between the triple point of water and the freezing point of water at standard pressure.

Comments

September 21, 2010 at 5:26 am
(1) kiya legesse says:

Hi! Madam,
Thank you for your unmeasurable sharing of knowledge. I am a teacher of chemistry and I was used the two words similarly to teach. But now I get their difference easly.

April 8, 2011 at 6:06 am
(2) Sherly says:

Thanks for sharing the difference. Its quite good

July 7, 2011 at 5:19 pm
(3) frank la roche says:

WHAT IS TRIPPLE POINT OF WATER MEAN ?

September 7, 2011 at 12:35 pm
(4) Kapilraj_mech says:

Triple is the point where the three phase such as solid, liquid and vapour is exiting.

August 5, 2011 at 1:08 am
(5) guddu says:

thanks a lot for ur valuable guidance

August 11, 2011 at 11:48 pm
(6) 32 and Sweltering says:

That’s hot. Precisely hot.

October 4, 2011 at 9:49 am
(7) Jon says:

This answer was very useful to me in my research as I have never understood the difference before.

Thanks

October 4, 2011 at 9:52 am
(8) Jonathan says:

sorry, i accidentally duplicated this comment.

October 4, 2011 at 9:51 am
(9) Jonathan says:

This answer was very useful to me in my research as I have never understood the difference before.

Thanks for the help.

October 31, 2011 at 5:49 pm
(10) Lari says:

Very helpful. Thank you

December 8, 2011 at 11:42 am
(11) Mursi says:

Thankyou to be here for our guidness, God bless you :-)

January 2, 2012 at 6:15 am
(12) Yashvee says:

Thanks now it is for me to understand chemistry better

January 18, 2012 at 12:31 pm
(13) Nige from Sheffield UK says:

You say it changed from centigrade to celcius in 1948 but we still used centigrade into the 1970′s plus

January 22, 2012 at 7:59 am
(14) ChandrashekaR Shetty says:

Thanks for sharing the knowledge..
Its very usefull…

January 29, 2012 at 3:02 pm
(15) Reza says:

I thing we have to name the Swedish astronomer Anders Celsius (17011744) who developed the temperature scale a few years before his death.

February 19, 2012 at 2:57 pm
(16) What? says:

I was tempted to take this seriously, but when you said “A degree Celsius (or a Kelvin)”, I decided to get a second opinion. Kelvins are not degrees Celsius. Thank you for your time, “doctor.”

February 28, 2012 at 11:51 pm
(17) Delta C = Delta K says:

A change of a degree Celsius is equal to change in one Kelvin. Delta C was implied by the statement. I certainly hope you were trolling.

March 14, 2012 at 2:04 am
(18) Subrat says:

Thanks a lot for sharing this difference in degree centigrade and Celsius.

March 30, 2012 at 2:00 pm
(19) Shyamal says:

Thank you for sharing the knowledge…

April 3, 2012 at 1:22 am
(20) Vara Kumar says:

Thanks, excellent explanation. very nice guidence.

Vara Kumar
Hyderabad-India

April 11, 2012 at 11:16 am
(21) g1cmz says:

I am sure i heard once that whilst both c and c have 100 degrees, one c originally had 100 as freezing and 0 as boiling.
Is there any truth to this?
And by the way, if grades are units what are they?
I’ve never heard of them (except in the context of exams rather than units).

April 14, 2012 at 2:13 am
(22) bruno says:

Anders Celsius defined the original Centigrade scale where the boiling point of water was 0 and freezing 100. After he died in 1744, Linnaeus defined it in the reverse direction with freezing at 0. In 1948, it was renamed Celsius because centigrade had other meanings in Spanish and French. Celsius, due to imprecise measurement at the time, turned out to be defined as slightly different from Centigrade. (Celsius doesn’t use either freezing point or boiling point in the definition. it uses absolute 0 and the triple point defined a 0.01 C). and they got that slightly wrong.

May 18, 2012 at 8:58 am
(23) anon says:

How disappointing that a teacher of chemistry doesn’t know the difference between celcius and centigrade, and worse, used the two terms interchangeably. Even worse still, relied on a questions forum to find out! Unbelievable.

May 24, 2012 at 10:28 am
(24) Madhumitha says:

I got so much info about celsius and centigrade scale.Thanks!

May 24, 2012 at 11:58 am
(25) Eldhose Scaria says:

Thank you very much for your kind information.
It helped me to clear a confusious discussion with. My father.

June 5, 2012 at 7:02 am
(26) Satish Joshi says:

Please tell me in detail about the thermodynamic range between absolute zero and triple point of specific water into 273.16 equal parts

June 7, 2012 at 3:33 pm
(27) Akhilesh kumar prajapati says:

Thank a lot whatever the guys are discussed about centigrade & celsius.

June 8, 2012 at 11:29 am
(28) argebe says:

How disappointing that ANON can’t spell Celsius. If you read his/her comment….believable!

July 6, 2012 at 9:04 am
(29) Chaitanya Raghav says:

People like ANON wont get sleep unless they fool themselves anyways Nice Explanation by Anne Marie Helmenstine

July 28, 2012 at 5:59 am
(30) sonal says:

i cant understand plz give me some extra example.

August 29, 2012 at 11:02 am
(31) Hima Bindu says:

hey thank u for conveying the difference between celsius and centigrade . I really browsed a lot for this but you conveyed it simply .

September 14, 2012 at 10:15 am
(32) Some Random Guy says:

People like anon just get their kicks by feeling smug and superior from pretending that they’re knowledgeable when the likelihood is that they aren’t. “What?” doesn’t seem to understand that, with the present definition of the Kelvin scale, the a difference of between 2 degrees of C is the same as the difference between 2 of K. Either that or they failed to understand the written English of the sentence. If “What?” had of understood either of these things they wouldn’t have posted such a disrespectful comment. Methinks: Trolls.

September 30, 2012 at 4:49 am
(33) buzz says:

I just came across this explanation and appreciate the precise answer.

Anon and What? Would like to feel superior. In fact all people who do so do it because they are in fact insecure at heart. Please keep up the good work

October 13, 2012 at 5:29 pm
(34) Jip2024 says:

I’m sure Anon and What r very intelligent, very beautiful, powerful and wealthy.. certainly don’t have anything to prove. The mirror is a scary place for most.. But most don’t feel it necessary to leak their insecurities like a bad dog seeking attention. I thought this was a fine, and simple explanation of the subject. Thank you for sharing the distinction.

October 19, 2012 at 7:25 am
(35) Manjunath says:

Thank u for your precious knowledge sharring…..

December 1, 2012 at 7:55 am
(36) Ferdous says:

Now I know:) Nicely explained..Thanks

December 4, 2012 at 7:28 pm
(37) HeMaCh says:

The centigrade scale was introduced in 1743 by Jean-Pierre Christin.

December 18, 2012 at 3:24 pm
(38) Graham says:

Triple point is where the three phases, ice, liquid and vapour exist in equilibrium.

December 29, 2012 at 11:40 am
(39) Prince kundi says:

It’s so good………..I love to get the knowledge about thing to which I have serious misapprehensive. Thanks for informing.

January 14, 2013 at 7:40 am
(40) Guy63689 says:

I find people from the UK are more likely to say centigrade over Celsius

January 22, 2013 at 12:09 pm
(41) David says:

Thank Dr. for your explanation I never really understood the diffrence before. Thank everyone for there input even the mean ones. Have a wonderful day everybody!

January 22, 2013 at 12:23 pm
(42) asmena says:

how does this scale deal with the heat involved in the change of state…I know that snow can sublimate and go directly from solid to gas, but?

February 14, 2013 at 7:03 am
(43) Lynne Diligent says:

I searched many places to find the REASON for this change (after the new name bothered me for years), and yours was the only site which included that reason. Thanks for writing this article.

February 20, 2013 at 2:46 am
(44) Siva says:

Thank you. very useful to me.

February 24, 2013 at 12:26 am
(45) Aytisi says:

It would be more accurate to say that Centigrade is the old name for the scale, which was abandoned by scientists and engineers in 1948 when the new name Celcius was adopted. Unfortunately, old habits are hard to break, so the name Centigrade hasn’t disappeared yet.

March 11, 2013 at 11:01 am
(46) Lemastre says:

It’s interesting to know the provenance of the terms Celsius and centrigrade vis-a-vis expressing temperature measurements. But it’s of no practical use, since in textbooks and articles, values are almost always written as degrees C and F. Authors don’t mention whether the C stands for centrigrade or Celsius, probably because common lab instruments don’t express, or should we say “bother with,” a difference as slight as might be needed to separate the two C scales.

March 11, 2013 at 2:16 pm
(47) Lemastre says:

It’s interesting to know the provenance of the terms centigrade and Celsius as regards temperature. But the difference isn’t of much practical use to students and probably to serious scientists, since the instruments we use apparently aren’t designed to take that difference into account or call it to our attention. In fact, at no point in my experience with chemistry at the undergraduate and graduate levels was the difference even alluded to.

March 12, 2013 at 9:00 am
(48) rajendran says:

Thanks very very thanks

April 17, 2013 at 1:24 am
(49) Mahsa says:

Thanks alot. It was helpful indeed.

April 18, 2013 at 10:58 pm
(50) Thorin N. Tatge says:

I didn’t find this terribly helpful. It seems like you never actually explain the difference between the two scales–you just say one is more precisely defined. The definition of a degree seems irrelevant to the rest.

April 27, 2013 at 3:43 pm
(51) manik sharma says:

Thanks a lot mam..

May 10, 2013 at 1:45 am
(52) jitender attri says:

Thank u mam

May 14, 2013 at 6:50 am
(53) Mickidona says:

Thank you, very helpful. I was watching a documentary and they used both Celsius and Centigrade. Now I understand that they are essentially the same thing. Thank you!

May 23, 2013 at 3:07 pm
(54) Dodi says:

Thank you. I learned to say Celsius instead
of centigrade . Also, how to spell Celsius .
Overseas, they don’t use Fahrenheit . Also learning to
Convert pound to kilos.

July 2, 2013 at 2:36 pm
(55) Fair Game says:

Anon can be measured in the degree of “jackassius”. Zero degrees jackassius is the point of which one is completely stupid, and one hundred degrees jackassius is the point of being a complete jack-ass. I would say Anon is at 100 J.

Keep keepin’ on Annie… thank you for your time and explanation.

July 13, 2013 at 2:49 pm
(56) DA Ward says:

thank you for explaining this for me

July 16, 2013 at 6:22 am
(57) CaliPedro says:

I have always scratched me head about this one. No rocket scientist but the son of a chemist (US def., not UK). Pappy just said the difference is basically inconsequential. At 5 I was using metric beakers and graduates in the kitchen and could do conversations in my head. Too bright by half.

Excellent, concise explanation.

Dear Graham, solid, liquid, vapour in equal equilibrium? WTF is that? S to L is one point, L to V is another. Triple point? Come again. Cheers.

How stupid is it that only the US, Myanmar, and Liberia still use Fahrenheit? I am resigned to living in a 3rd world backwater, er the States.

July 18, 2013 at 3:36 am
(58) The nationalist says:

a picture comparison would be helpful. A picture is worth a thousand words.

August 7, 2013 at 12:19 pm
(59) Ewurama Hinson says:

Thank you Anne Marie for the wonderful explanation. I was taalking to a friend and I used the expression degree centigrade and the friend repeated “degree celcius”. I haqd always used them interchangeably so I decided to research the difference. Your explanation makes it very clear. Thank you very much. Ama Ghana.

August 31, 2013 at 12:20 am
(60) Not strictly necessary says:

CaliPedro

I myself am not an expert upon the subject, but it is indeed possible to have more than one state of a element or material exist at one time, if the proper conditions, temp, pressure, etc. , are met. For example, even when below boiling point both liquid and gaseous H2O exist in our environment naturally.

September 5, 2013 at 10:54 pm
(61) Desert Tripper says:

I still say “centigrade.” It just sounds better to me. Not too fond of the change from “cycles per second” to “Hertz,” either. Cycles (cps), kc, mc, etc. are far more descriptive than somebody’s name. mmHg trumps Torr in my book, too.

What’s next? Shall we express wind speed in Albertis instead of miles per hour or knots (=nautical miles per hour) in honor of the inventor of the anemometer?

Measures that don’t have better descriptions (e.g. volts, amperes, henries, farads, etc.) are okay with me. It’s okay to honor famous people, but when it comes with the price tag of less descriptiveness, it doesn’t make much sense to me.

September 18, 2013 at 12:50 pm
(62) umashankar yadav says:

nice explaination yhanks

September 20, 2013 at 11:02 am
(63) JDon says:

@Desert Dripper: the change from cps to Hertz makes it more accessable to an international community. I am honestly suprised that kph hasn’t gotten changed to a proper name yet. Mph is unlikely to change because it’s an imperial unit, and those aren’t required to make sense… :)

September 25, 2013 at 7:50 am
(64) venu says:

i did’t get what is triple point of eater???

September 25, 2013 at 11:28 am
(65) Kevin Flynn says:

@”What?”
You commented negatively about the “Kelvin” reference.
She is correct. You have a conventional knowledge of the two measurement systems. She was not referencing the scales as a whole but rather a single unit. If you ARE familiar you do realize that there are points when all three (4) coincide to some degree. There is the entire scope of a scale and then there is an individual unit. It is true that AT SOME POINTS they are 273.16 apart. She is using this (or a Kelvin) precisely. “A” kelvin. Key point. here’s a reference:

“This definition fixes the magnitude of both the degree Celsius and the kelvin as precisely 1 part in 273.16 (approximately 0.00366) of the difference between absolute zero and the triple point of water. Thus, it sets the magnitude of one degree Celsius and that of one kelvin as exactly the same. ”

The last sentence being the most incriminating against your claim.

She simply is very literal and you were viewing in a more vague perspective. Language is key in any discussion.

October 2, 2013 at 7:52 am
(66) PeterP says:

To give a more exhaustive asnwer to the triple point question:
The phase of an element depends on temperature and pressure.
For each combination of temperature and pressure there exists a specific phase. For very high pressure, there are only two possible phases: liquid or ice. For low pressure, there are only vapour and ice. For high temperatures there are only vapour and liquid.
However, there is a certain combination of temperature and pressure where all three phases border each other. This happens at 0.00603ATM and 0.0098 centigrade (= 0°Celsius). This is the ‘triple point’ of water.

A demonstration how pressure affects the phase is the fact that you can easily slip on ice: the pressure of the soles shifts the phase change point of the ice, causing it to switch into a thin film of water on its surface. Without the need of applying heat. And there you go (or rather: fall). Below a certain temperature, ice will have as much grip as solid rock: the pressure of your weight won’t be enough for the phase shift anymore.

October 2, 2013 at 7:53 am
(67) PeterP says:

It should be noted that temperature, as well as pressure, is an average value. On molecular level, individual molecules have different kinetic energy. So those with a higher than average may break out of the current phase. This is why even cold water vaporizes (while the remaining liquid cools down) or ice can sublimate. Normally, the process reverses more or less immediately, unless the molecules are removed (e.g. by blowing on the hot coffee), or move away fast enough from the compound due to their own kinetic energy. (used in vacuum vaporization)

BTW: other units have too undergone a change in their definition. Like the second (from 1/86400 of a day to the time of n oscillations of the Cesium atom).
Or the switch 1m from 1/40,000,000 of the earth circumference, expressed by the length of a reference object (the Urmeter or ‘metre des archives’ = standard meter) with 443.440 paris lines (= 1000.325mm) to 1,650,763.73 wavelengths of Krypton (86Kr) spectral radiation in 1960.

October 11, 2013 at 7:05 am
(68) Sudhanshu Mishra says:

Very elaborative and precise answer.
Thanks alot.

November 12, 2013 at 10:24 am
(69) abhijith manu says:

thank you madom

November 16, 2013 at 4:02 am
(70) Pyae Thet Tun says:

Thank you a lot, I have not known this difference. Now I can see it clearly.

November 25, 2013 at 9:18 am
(71) yesbhagwat says:

it’s educative and interesting.

December 21, 2013 at 12:08 am
(72) loreleirobin says:

Why aren’t fahrenheit and celsius scrabble words but centrigrade and kelvin are accepted?

January 7, 2014 at 7:59 am
(73) Paulustrious says:

<b> A Matter of Degree</b>

A problem we have is the word degree. The word meter (or foot) defines the difference between two points. Degree also means a difference. But it can also mean an absolute measurement. So 100 degrees Kelvin means the same as 100 degrees Celsius in terms of the difference between boiling and freezing. It absolutely does not mean the same when referring to temperature. ‘Tis a pity we don’t have two words.

@PeterP – Well done.

January 8, 2014 at 1:10 am
(74) TonyP says:

Thank you for the explanation. Very informative.

@Paulustrious – The word meter does not define the difference between two points; it describes the magnitude of this difference. The difference between two points is defined by an equation (e.g., the distance formula).

Degree is defined as a set change in temperature measured against a given scale (It also alludes to the fact that the scale’s zero is an arbitrary number, but that is not always the case).

The only time the term degree is used to describe absolute measurement of temperature is when one speaks of degrees Rankine. Simply put, you don’t say “degrees Kelvin.” You can just say Kelvin.

I think what you were trying to say was that the magnitudes of a Kelvin and a degree Celsius are the same, therefore when determining delta_T, or the difference between boiling and freezing, it does not matter if it is expressed in K or degree C.

February 5, 2014 at 9:56 pm
(75) Senti Gradinski says:

This is PRECISELY the kind of information that my mother NEVER told me!

Thanks!

February 23, 2014 at 12:24 pm
(76) jucalon says:

This answer is given by a PhD! therefore it should be reliable, provided of course, the doctor has a PhD in something related to the subject!

February 23, 2014 at 1:01 pm
(77) jucalon says:

Ewurama Hinson

What do you use now? The answer says they are essentially the same temperatura scale (with slight differences). In the comments we find the centigrade scale was invented by Celsius, and I suppose they renamed it after him in the 40s to honor him. In Colombia we commonly use “grados centígrados”, not Celsius. Maybe we are not following auniversal mandate, and we should…

February 27, 2014 at 6:03 pm
(78) douglas Marriott says:

There is a difference?

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