100°F to Celsius = 37.8°C

Fahrenheit to Celsius conversion table
°F	°C	Reference point
−40	−40	Both scales read the same
−20	−28.89
0	−17.78	Freezer setting
10	−12.22
20	−6.67
32	0	Water freezes
40	4.44	Refrigerator limit
50	10
60	15.56
65	18.33
68	20	Room temperature
70	21.11
72	22.22
75	23.89
80	26.67
85	29.44
90	32.22
95	35
97	36.11
98	36.67
98.6	37	Traditional normal body temp
99	37.22
100	37.78
100.4	38	Fever threshold
101	38.33
102	38.89
103	39.44
104	40	High fever
110	43.33
120	48.89
145	62.78	Whole cuts of beef, pork (USDA)
160	71.11	Ground meat (USDA)
165	73.89	Poultry (USDA)
212	100	Water boils at sea level
250	121.11
300	148.89
325	162.78
350	176.67	Moderate oven
375	190.56
400	204.44
425	218.33
450	232.22
500	260

100 °F at a glance

Celsius: 37.78 °C
Exact fraction: 37 7/9 °C
Kelvin: 310.93 K
Rankine: 559.67 °R
Rounded: 38 °C
Quick estimate: 35 °C

How to convert 100 °F to Celsius

°C = (°F − 32) × 5/9
(100 − 32) × 5/9 = 68 × 5/9 = 340/9 = 37.78 °C

Subtract 32 first because the two scales put zero in different places, then multiply by 5/9 because a Fahrenheit degree is only 5/9 the size of a Celsius degree. 68 is not a multiple of 9, so the exact answer is the repeating decimal 37 7/9 °C.

Estimate it in your head

Subtract 30 and halve: (100 − 30) ÷ 2 = 35 °C. That is 2.8 degrees low, close enough to decide what to wear.

100 °F on a thermometer and in the weather

Just under a fever. The CDC counts 100.4 °F (38 °C) or higher as a fever, so a reading of 100 °F is elevated but not yet a fever by that definition.
As weather. An air temperature of 100 °F (37.78 °C) is a heat wave in most of the US; in dry desert air the heat index is close to the air temperature, but humid air pushes it much higher:

Relative humidity	Heat index	NWS category
10%	94 °F	Extreme caution
25%	100 °F	Extreme caution
40%	109 °F	Danger

Temperatures near 100 °F

Fahrenheit	Celsius	Kelvin
95 °F	35 °C	308.15 K
96 °F	35.56 °C	308.71 K
97 °F	36.11 °C	309.26 K
98 °F	36.67 °C	309.82 K
99 °F	37.22 °C	310.37 K
100 °F	37.78 °C	310.93 K
101 °F	38.33 °C	311.48 K
102 °F	38.89 °C	312.04 K
103 °F	39.44 °C	312.59 K
104 °F	40 °C	313.15 K
105 °F	40.56 °C	313.71 K

Going the other way: 38 °C in Fahrenheit is 100.4 °F.

Frequently asked questions

What is 100 °F in Celsius?

100 °F is 37.78 °C: subtract 32 (68) and multiply by 5/9.

Is 100 °F hot or cold?

100 °F is around human body temperature — just under a fever, and a heat wave as weather.

How do you convert 100 °F to Celsius in your head?

Subtract 30 and divide by 2: (100 − 30) ÷ 2 = 35 °C, compared with the exact 37.78 °C.

What is 100 °F in Kelvin?

100 °F is 310.93 K. Convert to Celsius (37.78 °C) and add 273.15.

Need a different value? Use the Fahrenheit to Celsius converter, or browse the Fahrenheit to Celsius chart.

Sources: Wind chill and heat index use the US National Weather Service formulas. Health and food-safety thresholds are from the CDC, FDA, USDA, CPSC and US Department of Energy.

100 °F to °C

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