Comparison of temperature scales

Table of selected points

The following table gives a comparison of the numerical value of temperatures on a number of different scales:

	Kelvin	Celsius	Fahrenheit	Rankine	Delisle	Newton	Réaumur	Rømer
Absolute zero	0	−273.15	−459.67	0	559.725	−90.14	−218.52	−135.90
Fahrenheit's ice/salt mixture	255.37	−17.78	0	459.67	176.67	−5.87	−14.22	−1.83
Water freezes (at standard pressure)	273.15	0	32	491.67	150	0	0	7.5
Average human body temperature (See note below)	310.0	36.8	98.2	557.9	94.5	12.21	29.6	26.925
Water boils (at standard pressure)	373.15	100	212	671.67	0	33	80	60
Titanium melts	1941	1668	3034	3494	−2352	550	1334	883
The surface of the Sun	5800	5526	9980	10440	−8140	1823	4421	2909

Note: Normal human body temperature is 36.8 °C ±0.7 °C, or 98.2 °F ±1.3 °F. The commonly given value 98.6 °F is simply the exact conversion of 37 °C, and therefore has excess (invalid) precision. Some numbers in this table have been rounded off.

Formulas for conversion

Given any two fixed points, the formula for conversion between any two scales in the table above can be determined. If two rows and two columns appar as:

	Scale X	Scale Y
Fixed point 1	a	b
Fixed point 2	c	d

the formula can be derived:

$(^\circ Y) = p(^\circ X) + q$

where

$p = {b - d \over a - c}$

and

$q = {ad - bc \over a - c}$.

Chart of conversions between the different temperature units