Temperature Converter: Celsius, Fahrenheit, Kelvin

Last updated: October 2026

From

Formula

°F = °C × 9/5 + 32

Water freezes 0 °C = 32 °F
Body temperature 37 °C = 98.6 °F
Water boils 100 °C = 212 °F
-40 °C = -40 °F

All Results

°C 1

°F 33.8

K 274.15

°R 493.47

Quick Reference Table: Celsius → Fahrenheit

Value (°C)	Result (°F)
-40 °C	-40 °F
-20 °C	-4 °F
-10 °C	14 °F
0 °C	32 °F
10 °C	50 °F
20 °C	68 °F
25 °C	77 °F
30 °C	86 °F
37 °C	98.6 °F
40 °C	104 °F
100 °C	212 °F

How to Convert Temperature Units

You need to convert temperatures in the kitchen, in science, when traveling and in everyday life. The most common conversion is between Celsius (°C), used in most countries, and Fahrenheit (°F), used mainly in the United States. To convert Celsius to Fahrenheit, multiply by 9/5 (or 1.8) and add 32. To convert Fahrenheit to Celsius, subtract 32 and multiply by 5/9. The kelvin (K) is the SI unit of thermodynamic temperature, used in science and engineering. Its scale starts at absolute zero (0 K = −273.15 °C). The Rankine scale is the imperial counterpart of the Kelvin scale.

Everyday Temperatures

Reference points people actually look up, from a home freezer to an oven setting. Celsius and Fahrenheit meet at −40°.

Situation	°C	°F	K
Absolute zero	-273.15	-459.67	0
Liquid nitrogen boils	-195.8	-320.44	77.35
Home freezer	-18	-0.4	255.15
Water freezes	0	32	273.15
Refrigerator	4	39.2	277.15
Room temperature	21	69.8	294.15
Human body	37	98.6	310.15
Fever	38.5	101.3	311.65
Hot bath	40	104	313.15
Finnish sauna	80	176	353.15
Water boils (sea level)	100	212	373.15
Oven, moderate	180	356	453.15
Oven, hot	220	428	493.15
Candle flame	1,000	1,832	1,273.15
Sun's surface	5,505	9,941	5,778.15

History of temperature scales

It took about three centuries to go from rival thermometers, each with its maker's own reference points, to a definition based on a fixed constant of nature.

1724 Daniel Gabriel Fahrenheit described his scale in the Royal Society's Philosophical Transactions: 0 was a mixture of ice, water and salt, 32 ice and water alone, and 96 the temperature of a healthy person.
1742 Anders Celsius published a 100-degree scale with 0 at the boiling point of water and 100 at its freezing point.
1743–1745 The scale was reversed to today's direction, 0 for freezing and 100 for boiling. Several people are credited, including Jean-Pierre Christin in Lyon and Carl Linnaeus in Uppsala.
1848 William Thomson, later Lord Kelvin, proposed an "absolute" temperature scale that does not depend on the properties of any particular substance.
1854 Thomson and James Joule proposed the absolute scale that today's kelvin is based on. Its zero is absolute zero, the lowest possible temperature, which can be approached but never reached.
1859 William Rankine gave temperatures in Fahrenheit-sized degrees counted from absolute zero; the scale was later named after him.
1948 The name "degree Celsius" was adopted internationally, replacing "degree centigrade".
1967 The unit was named the kelvin, symbol K, replacing "degree Kelvin" (°K).
2019 The kelvin was redefined by fixing the Boltzmann constant at exactly 1.380649 × 10⁻²³ J/K.

Sources:

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