104°F to Celsius = 40°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

104 °F at a glance

Celsius: 40 °C
Exact fraction: 40 °C
Kelvin: 313.15 K
Rankine: 563.67 °R
Rounded: 40 °C
Quick estimate: 37 °C

How to convert 104 °F to Celsius

°C = (°F − 32) × 5/9
(104 − 32) × 5/9 = 72 × 5/9 = 360/9 = 40 °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. Here 72 divides evenly by 9, so the answer is a whole number.

Estimate it in your head

Subtract 30 and halve: (104 − 30) ÷ 2 = 37 °C. That is 3 degrees low, close enough to decide what to wear.

104 °F on a thermometer and in the weather

Hot tub maximum. The US Consumer Product Safety Commission says hot tub water should never be hotter than 104 °F (40 °C). As a body temperature, 104 °F is a high fever that needs medical attention.
As weather. An air temperature of 104 °F (40 °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%	98 °F	Extreme caution
25%	106 °F	Danger
40%	119 °F	Danger

Temperatures near 104 °F

Fahrenheit	Celsius	Kelvin
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
106 °F	41.11 °C	314.26 K
107 °F	41.67 °C	314.82 K
108 °F	42.22 °C	315.37 K
109 °F	42.78 °C	315.93 K

Going the other way: 40 °C in Fahrenheit is 104 °F.

Frequently asked questions

What is 104 °F in Celsius?

104 °F is 40 °C: subtract 32 (72) and multiply by 5/9.

Is 104 °F hot or cold?

104 °F is around human body temperature — a fever if it is your body temperature, and a heat wave as weather.

How do you convert 104 °F to Celsius in your head?

Subtract 30 and divide by 2: (104 − 30) ÷ 2 = 37 °C, compared with the exact 40 °C.

What is 104 °F in Kelvin?

104 °F is 313.15 K. Convert to Celsius (40 °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.

104 °F to °C

Show the work