About

Centigrade and Celsius denote the same temperature scale. The term centigrade (Latin: centum = 100, gradus = step) was replaced by Celsius in 1948 by the 9th General Conference on Weights and Measures (CGPM, Resolution 3). The rename resolved ambiguity with the angular unit centigrade (1⁄100 of a gradian) still used in French and Spanish surveying. A value of 25 °centigrade is exactly 25 °C - no arithmetic conversion exists between them. This tool confirms that identity and simultaneously converts your input to 7 additional scales (Fahrenheit, Kelvin, Rankine, Réaumur, Delisle, Newton, Rømer) using ITS-90 standard reference formulas.

Errors in temperature conversion propagate directly into calorimetry, HVAC load calculations, and material stress analysis. A misread of 10 °C in a steel tempering schedule shifts yield strength outside specification. This converter applies exact rational coefficients - for instance, the Fahrenheit factor is the ratio 95 not the truncated decimal 1.8 - to preserve precision across the full range from absolute zero (−273.15 °C) upward. Note: formulas assume standard atmospheric pressure and do not account for ITS-90 interpolation polynomials below 13.8033 K.

Formulas

Centigrade and Celsius are identical. The numeric value is unchanged:

T_°C ≡ T_°centigrade

Conversions from Celsius (C) to other scales:

F = C × 95 + 32

K = C + 273.15

Ra = (C + 273.15) × 95

Ré = C × 45

De = (100 − C) × 32

N = C × 33100

Rø = C × 2140 + 7.5

Where C = temperature in degrees Celsius (identical to degrees centigrade), F = Fahrenheit, K = Kelvin (absolute thermodynamic scale), Ra = Rankine, Ré = Réaumur, De = Delisle (note: inverted scale, higher values = colder), N = Newton scale, Rø = Rømer. Kelvin cannot fall below 0 K (absolute zero = −273.15 °C).

Reference Data

Temperature Scale	Symbol	Zero Point	Boiling Point H&sub2;O	Absolute Zero	Invented	Usage
Celsius (Centigrade)	°C	0 °C	100 °C	−273.15 °C	1742	Global scientific & daily use
Fahrenheit	°F	32 °F	212 °F	−459.67 °F	1724	USA, Bahamas, Cayman Islands
Kelvin	K	273.15 K	373.15 K	0 K	1848	SI base unit, thermodynamics
Rankine	°Ra	491.67 °Ra	671.67 °Ra	0 °Ra	1859	US engineering thermodynamics
Réaumur	°Ré	0 °Ré	80 °Ré	−218.52 °Ré	1730	Historic (France, cheese-making)
Delisle	°De	150 °De	0 °De	559.725 °De	1732	Historic (Russia, 18th c.)
Newton	°N	0 °N	33 °N	−90.14 °N	1700	Historic (Isaac Newton)
Rømer	°Rø	7.5 °Rø	60 °Rø	−135.90 °Rø	1701	Historic (Ole Rømer)
Gas Mark	GM	-	-	-	1920s	UK cooking (starts at 135 °C)
Leiden Scale	°L	-	-	−253 °L	1894	Cryogenics (historical)
Planck Temperature	T_P	-	-	0	1899	Theoretical physics limit
Wedgwood	°W	-	-	-	1782	Historic pottery kiln temps

Frequently Asked Questions

No. The scales are numerically identical. In 1948, the 9th CGPM renamed "centigrade" to "Celsius" (Resolution 3) to eliminate confusion with the angular unit "centigrade" (1/100 of a gradian) used in French and Spanish surveying. A reading of 37 °centigrade equals exactly 37 °C with zero conversion factor applied.

Absolute zero (−273.15 °C = 0 K) is the lower bound of thermodynamic temperature. The Kelvin and Rankine scales are absolute scales that start at this point. Any input below −273.15 °C produces physically meaningless results for Kelvin and Rankine - this tool flags such inputs. Celsius and Fahrenheit permit negative values, but no real system can exist below absolute zero per the third law of thermodynamics.

This tool uses exact rational coefficients (9/5, 4/5, 33/100, 21/40, 3/2) rather than rounded decimals. For example, using 1.8 instead of 9/5 introduces floating-point drift at high magnitudes. JavaScript's IEEE 754 double-precision arithmetic carries approximately 15-17 significant digits, so results remain accurate for any temperature within ±10¹⁵ °C. Results are displayed rounded to 4 decimal places for readability.

Yes. The Delisle scale runs in reverse: higher Delisle values correspond to lower temperatures. Water boils at 0 °De and freezes at 150 °De. The formula De = (100 − C) × 3/2 reflects this inversion. This was Joseph-Nicolas Delisle's original 1732 design, calibrated for Russian meteorological observations where colder readings were more frequent and thus assigned larger numbers.

Réaumur (°Ré) still appears in European cheese-making and some Italian food processing where traditional recipes specify fermentation temperatures in Réaumur. The Newton scale (°N) is purely historical - Isaac Newton used it around 1700 for his linseed oil thermometer experiments. Neither scale has any modern SI or NIST endorsement, but legacy industrial documentation may reference them.

In calorimetry, a 1 °C error in a 500 kg water system at specific heat 4.186 kJ/(kg·K) yields an energy error of 2,093 kJ - enough to missize a heat exchanger by roughly 0.58 kWh. In metallurgy, tempering steel at 205 °C vs. 215 °C shifts Rockwell hardness by approximately 2 HRC points, potentially pushing a component outside specification. Always verify scale identity before calculation.