Centigrade or celsius?

Updated April 24, 2017

By Jon Zamboni

The distinction between the Celsius and centigrade scales can seem confusing — but the two terms refer to the same scale of measurement, and both use the same degree designation — degrees C.

The two scales — Centigrade and Celsius — originated in the 18th century, and were used interchangeably until the mid-20th century.

Although some people might still use the term centigrade on occasion, the official term is Celsius.

Centigrade or Celsius?

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The names Celsius and centigrade date back to the scale’s two originators. In 1742, Swedish scientist Anders Celsius designed a temperature scale that used 0 degrees as the boiling point of water and 100 degrees as the freezing point.

One year later, French scientist Jean Pierre Cristin designed a similar temperature scale: Cristin's scale used the same divisions as Celsius's scale, but Cristin’s scale set the freezing point at 0 degrees and the boiling point at 100 degrees.

Cristin called his scale the centigrade scale, because it was divided into 100 parts, with centi as the prefix for 100.

The Celsius/centigrade scale in use today is Cristin's, but it was interchangeably referred to as either Celsius or centigrade in different regions of the world.

Centigrade or Celsius?

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In 1948, 33 nations met for the 9th General Conference on Weights and Measures.

This conference was a meeting of countries to determine the standards of measurement used in those countries — these conferences were established in 1875 by a treaty known as the Convention of the Metre — also known as the Treaty of the Meter. At the 1948 conference, the centigrade/Celsius scale was officially designated the Celsius scale in honor of Anders Celsius.

About the Author

Jon Zamboni began writing professionally in 2010. He has previously written for The Spiritual Herald, an urban health care and religious issues newspaper based in New York City, and online music magazine eBurban. Zamboni has a Bachelor of Arts in religious studies from Wesleyan University.

centigrade andCelsius temperature scales

Download a printable,
letter-size chart for converting between Fahrenheit and Celsius visually.

From Celsius' paper.

In 1741 Anders Celsius, professor of astronomy at
the University of Uppsala, Sweden, introduced a temperature scale with 0 the
temperature at which water boiled and 100 the temperature at which water froze.

No later than 1745 his colleague and close friend, the botanist
Carl von Linné (Linnaeus of taxonomic fame) introduced in his greenhouses
thermometers with 0 at freezing and 100 at boiling, and Linnaeus would later say
he invented the scale.

In 1743, in Lyon, France, Jean
Pierre Christin introduced a thermometer with a 0 freezing, 100 boiling, scale,
although his understanding of the role of fixed points in a thermometric scale
was probably faulty.

The Réaumur scale
remained the overwhelming favorite in France, but a number of thermometers
graduated in Christin's scale were exported to England, where they were known as
“Lyon thermometers.”

Celsius died in 1744. Perhaps Linneaus refrained
from changing the scale while his patron was alive. By 1747,
Celsius' successor, Märten Strömer, was hanging thermometers with the inverted
scale.

On
13 April 1750, the Swedish records began to be
published in the inverted scale (0 degrees the freezing point of water and 100
degrees its boiling point at atmospheric pressure) which we now use.

The scale
became known as the centigrade scale.¹

In 1887 the International Commission on Weights and
Measures adopted “as the standard thermometric scale for the international
services of weights and measures the centigrade scale of the hydrogen
thermometer, having as fixed points the temperature of melting ice (0°) and the
vapor of distilled water boiling (100°) at standard atmospheric pressure, the
hydrogen being taken at an initial manometric pressure of one meter of mercury.”

The Celsius scale is the centigrade scale with one change. Defined in
1954 at the 10th General Conference of Weights and Measures, temperature
on the Celsius scale is the temperature on the Kelvin scale minus 273.15.

This definition makes values on the Celsius and centigrade scale agree within
less than 0.1 degree.  For everyday purposes, the scales are
identical.

  One reason for doing away with the word “centigrade,” was that
it might be confused with one-hundredth of a grade, a
unit of plane angle.

Why was the centigrade scale abandoned?

The problem was that the ice point, the “temperature of melting ice…at
standard atmospheric pressure,” which was used to define zero degrees on the
centigrade scale, cannot be measured with enough precision.

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Ideally one takes
the temperature of a bath of pure, air-saturated water containing pure melting
ice. But as ice melts it surrounds itself with a layer of insulating meltwater
that is not air-saturated.

The bath cannot be stirred because that would heat
it.

In contrast, the Kelvin scale has a nearby set point, the triple point of
water. The triple point is the temperature and pressure at which water can exist
simultaneously as a solid, liquid and gas. Measurements of the temperature of
the triple point are reproducible with an variation of 0.

000 050 K or less. By
the definition of the Kelvin scale the triple point of water is 273.16 kelvin.
Replacing the hard-to-measure ice point with the triple point made possible more
precise measurements. To indicate the change, the “zero is freezing, 100 is
boiling” scale was given a new name.

Converting between degrees Celsius and Fahrenheit

Centigrade or Celsius?               
Centigrade or Celsius?

1. For a detailed, unsurpassed discussion of the origin of the centigrade
scale, see chapter 4 of:

W. E. Knowles Middleton.
A History of the Thermometer and its Uses in Meteorology.
Baltimore, MD: The Johns Hopkins Press, 1966.

Copyright © 2000 Sizes, Inc.  All rights reserved.
Last revised: 1 March 2011.

Temperature Conversion: Convert between Celsius, Kelvin, and Fahrenheit

Centigrade or Celsius?

Understanding Celsius

  • 0° – Freezing
  • 10° – Cold
  • 20° – Room Temperature
  • 30° – Hot
  • 40° – Sweltering

Temperature Fun Facts

Enter a value for any one of the three temperature scales and the others will
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The calculator follows proper rounding rules for scientific purposes.

The formulas used to convert between temperatures are as follows:

  • °C = (°F – 32) * 5 / 9
  • °F = (°C * 1.8) + 32
  • K = °C + 273.15
  • °C = K – 273.15

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About Temperature Conversion

The fahrenheit was proposed by Daniel Gabriel Fahrenheit. The scale is often mispelled as “farhenheit”, “farenheit”, “farhenhiet”, or “farenhiet”.

The Celcius scale is still sometimes called the “centigrade” scale because it is divided into 100 divisions. It was devised by Andres Celsius.

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Copyright Stephen Ostermiller 2001-2014

What Happened to Centigrade? Confusion Over the Celsius Temperature Scale…

When I started teaching elementary school (as a second career in 1995), I was very surprised to find all the new textbooks now referring to the centigrade scale as the Celsius scale. Of course they are the same thing, but I wondered why the textbooks were now using this term when I had never heard it growing up. Now, I know why.

The short answer is that people continue to call a thing by the same name they, themselves, learned while growing up.  Most adults, and just about everyone in academia through the 1980s, grew up hearing “centigrade” and continued to use that term with their own students throughout high school and university.

The new name, “Celsius,” disturbed me ever since I began hearing it in the mid-1990s; but now that I know there was an actual reason for the name change, it no longer bothers me.  A unit of measurement, called a “grade,” was actually in use.  Therefore, in 1948, the Conference General de Pois et Measures (in France) decided to change the name of the scale to “Celsius.”

The International System of Units

A second reason for the change in name was that the Conference General de Pois et Measures decided that “All common temperature scales would have their units named after someone closely associated with them; namely, Kelvin, Celsius, Fahrenheit, Réaumur and Rankine.”

The change in elementary-school textbooks began to take place around 1968, and during the 1970s, as districts began to replace their former textbooks.

 In the meantime, parents, scientists, and college professors continued to use the name they had grown up with.  Only students born in the 1970s and later would have grown up calling the scale “Celsius.

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”  (I continue to catch myself saying “centigrade” to my own students.)

In England, the BBC Weather did not begin using the term Celsius until 1985, and the word centigrade continues to to be commonly used in England, according to some sources.

Centigrade or Celsius?

Swedish Astronomer Anders Celsius (1701-1744)

The centigrade scale was known as such from 1743-1954.

 In 1948, the scale was renamed the Celsius scale, after the Swedish astronomer Anders Celsius (1701-1744) who developed a SIMILAR scale (but not actually the same scale).

 Interestingly, Celsius’ original scale was the reverse of today’s scale; “0” indicated the boiling point of water, while “100” indicated the freezing point of water.

Swedish Zoologist and Botanist Carolus Linnaeus(1708-1777)

The Swedish zoologist and botanist, Carolus Linnaeus (1707-1778), remembered for giving us the basis of taxonomy (classification of living things into genus and species), reversed Celsius’ original scale so that “0” indicated the freezing point of water, while “100” indicated the boiling point. As the older generations retire and pass away, the new name change will become universal.  It seems to take about three generations for a name change to really become universally accepted in society.

–Lynne Diligent

Celsius, Centigrade and Fahrenheit

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  • Celsius, Centigrade and Fahrenheit

What is Celsius?

°C

  • This is the most common temperature scale in the world and the simplest to understand.
  • Put simply, 0°C is the freezing point of water and 100°C is the boiling point of water.
  • Centigrade is an old fashioned name for Celsius.
  • You can abbreviate it to °C.
  • The scale is named after Swedish scientist Anders Celsius (1701-1744).

What is Fahrenheit?

°F

  • Fahrenheit is still in everyday use in the USA and preferred by older people in the UK.
  • In Fahrenheit the freezing point of water is 32°F and the boiling point is 212°F.
  • You can abbreviate it to °F.
  • The scale is named after its originator Gabriel Fahrenheit (1686-1736).

So what was Centigrade?

  • Centigrade is the old fashioned name for Celsius.
  • The name Centigrade was derived from the latin – meaning hundred degrees.
  • When Anders Celsius created his original scale in 1742 he inexplicably chose 0° for the boiling point and 100° for the freezing point.
  • One year later Frenchman Jean Pierre Cristin proposed an inverted version of the scale (freezing point 0°, boiling point 100°). He named it Centigrade.
  • In 1948, by international agreement, Cristin's adapted scale became known as Celsius to honour the Swedish Scientist.

What is the difference between them?

  • Celsius, Centigrade & Fahrenheit are all temperature scales.
  • All thermometer temperatures can be expressed in Celsius or Fahrenheit.
  • Both scales have the same value at -40°: -40°C = -40°F
  • To convert between Celsius or Fahrenheit you can use the following equations:
  • °C = °F – 32 x (5/9)
  • °F = °C / (5/9) + 32

What Is the Difference Between Celsius and Centigrade?

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 is a type of centigrade scale.
  • A centigrade scale has 100 degrees between the freezing and boiling points of water.
  • The original Celsius scale actually had a boiling point of 0 degrees and freezing point of 100 degrees. It ran in the opposite direction of the modern scale!

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.

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01°C difference between the triple point of water and the freezing point of water at standard pressure.

The temperature scale created by Anders Celsius in 1742 was actually the reverse of the modern Celsius scale. Celsius' original scale had water boil at 0 degrees and freeze at 100 degrees.

Jean-Pierre Christin independently proposed at a temperature scale with zero at the freezing point of water and 100 was the boiling point (1743).

Celsius' original scale was reversed by Carolus Linnaeus in 1744, the year in which Celsius died.

The centigrade scale was confusing because “centigrade” was also the Spanish and French term for a unit of angular measurement equal to 1/100 of a right angle.

When the scale was extended from 0 to 100 degrees for temperature, centigrade was more properly hectograde. The public was largely unaffected by the confusion.

Even though the degree Celsius was adopted by international committees in 1948, weather forecasts issued by the BBC continued to use degrees centigrade until February 1985!

Celsius to Fahrenheit (°C to °F)

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Celsius to Fahrenheit conversion is probably the most confusing conversion there is, but a simple °C to °F conversion is actually quite easy – just double the °C figure and add 30. This should be reasonably accurate for weather temperatures.

Absolute Zero

Parity

Freezing point

Body Temperature

Boiling point

-273.15°C -459.67°F
-40.00°C -40°F
0°C 32°F
37°C 98.6°F
100°C 212°F

Celsius and Fahrenheit definition

The Celsius temperature range was originally defined by setting zero as the temperature at which water froze. Zero degrees C was later redefined as the temperature at which ice melts. The other point at which Celsius was set – 100 degrees Celsius – was defined as the boiling point of water.

Since its definition, the Celsius scale has been redefined to peg it to Kelvin. Zero degrees Celsius is now defined as 273.15K. As one degree Celsius is equal to one Kelvin, boiling point of water is equal to 273.15 + 100 = 373.15 Kelvin.

Centigrade or Celsius?

Anders Celsius was a Swedish astronomer who invented a thermometer based on the boiling point and freezing point of water. We know a slightly improved version of his thermometer by the Celsius name and by the word centigrade.

The words Celsius and centigrade mean the same thing, but style guides say don’t bother with centigrade anymore, use Celsius.

The original Celsius thermometer had water boiling at 0 degrees and freezing at 100 degrees. Others scientists flipped those numbers for more practical measurements of extreme heat. Each degree of temperature later was called centigrade, from the Latin words centum and gradus, or 100 steps. 

This centigrade thermometer was named in honor of Celsius in 1948 at the ninth International Conference of Weights and Measures. Since then, degrees centigrade has diminished in use and degrees Celsius has become the more common term.

Celsius is capitalized just as we capitalize Fahrenheit, named for a German physicist, and Kelvin, named for a British physicist. (Just to make things more complicated, Kelvin is capitalized when you're writing about the scale itself, but lowercase when it's used as the unit. Also, Celsius and Fahrenheit use degrees, but Kelvin doesn’t.)

Style guides agree that Celsius should be used instead of centigrade, but they disagree on how to write the abbreviated form, except that there is no need for a period after C.

The Associated Press Stylebook doesn’t use the degree symbol and puts a space between the number and the symbol: 32 C. Scientific Style and Format uses the symbol and puts a space after the numeral: 32 °C.

The Chicago Manual of Style and the National Geographic Style Manual say no spaces: 32°C, and that seems to be the prevalent format.

Sources: Online editions of Oxford English Dictionary, Merriam-Webster Unabridged Dictionary, American Heritage Dictionary, Associated Press Stylebook, Chicago Manual of Style, Scientific Style and Format, National Geographic Style Manual, Encyclopedia of World Biography, Wikipedia, and Henry Carrington Bolton’s Evolution of the Thermometer 1592-1743 (1900).

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