Fahrenheit to Celsius Converter

About this tool

Type a temperature in Fahrenheit and the Celsius value appears instantly, or type in Celsius to go the other way. The conversion uses the exact formula, and everything runs in your browser. It is the quick answer to searches like "100 fahrenheit to celsius" or "f to celsius".

How to use it

Enter the temperature in the left box to get Celsius on the right. Negative numbers work, so -40 returns -40, the one point where both scales agree. Decimals are fine for body temperature, such as 98.6.

The formula: Fahrenheit to Celsius

Subtract 32, then multiply by 5/9. For 100 °F: 100 - 32 = 68, and 68 x 5/9 = 37.8 °C. To go back, multiply Celsius by 9/5 and add 32.

A quick mental shortcut

Subtract 30 and halve the result. For 80 °F that gives 25, and the exact answer is 26.7 °C. It is within about 2 degrees across normal weather, which is fine for deciding what to wear but not for baking or health readings.

Fahrenheit to Celsius chart

Fahrenheit	Celsius
0 °F	-17.8 °C
20 °F	-6.7 °C
32 °F	0.0 °C
40 °F	4.4 °C
50 °F	10.0 °C
60 °F	15.6 °C
70 °F	21.1 °C
72 °F	22.2 °C
80 °F	26.7 °C
90 °F	32.2 °C
100 °F	37.8 °C
110 °F	43.3 °C

Body temperature and fever in Fahrenheit and Celsius

Average body temperature is about 98.6 °F (37 °C), though normal varies by person and time of day. A reading of 100.4 °F (38 °C) or higher is generally treated as a fever. If you are worried about a fever, especially in an infant, an older adult or someone with a health condition, contact a doctor or nurse line rather than relying on a chart.

Fahrenheit	Celsius	Meaning
97.0 °F	36.1 °C	Low normal
98.6 °F	37.0 °C	Average body temperature
99.5 °F	37.5 °C	Upper normal
100.4 °F	38.0 °C	Fever threshold
101.0 °F	38.3 °C	Fever
102.0 °F	38.9 °C	Moderate fever
103.0 °F	39.4 °C	High fever
104.0 °F	40.0 °C	Very high fever

Oven temperatures in Celsius

US recipes use Fahrenheit, while most other countries use Celsius. Oven dials are often rounded to the nearest 5 or 10 degrees, so round the result to match your oven.

Oven setting	Celsius
250 °F	121 °C
300 °F	149 °C
325 °F	163 °C
350 °F	177 °C
375 °F	191 °C
400 °F	204 °C
425 °F	218 °C
450 °F	232 °C
475 °F	246 °C
500 °F	260 °C

Things to watch out for

Do not use the subtract-30-and-halve shortcut for baking, lab work or medical readings. A temperature difference is not converted the same way as a reading: a change of 18 °F is a change of 10 °C, with no 32 involved. Also check that a source is not already in Celsius, because 38 reads as a fever in Celsius and as a cold day in Fahrenheit.