What Is 103°F in Celsius?
103 degrees Fahrenheit is 39.4444 degrees Celsius.
How to Convert Fahrenheit to Celsius
To convert degrees Fahrenheit to degrees Celsius, subtract 32, then multiply by 5/9.
For example: 75 °F − 32 = 43, and 43 × 5/9 = 23.8889 °C.
Where You Meet This Number
At 103 °F American guidance starts advising people to contact a doctor for adults, and in Celsius that is 39.4 degrees — just under the 40-degree mark that reads as alarming to anyone raised on the metric scale.
A thermometer showing 103 °F is 39.4 °C, close to the 40 °C that most Celsius-raised readers think of as a serious fever.
What People Get Wrong
Fever-reducing medicine lowers the reading without changing the illness. A temperature that drops to 100 °F an hour after paracetamol has not resolved; it is masked, and the underlying reason still matters.
Body Temperatures in Fahrenheit and Celsius
| Degrees Fahrenheit (°F) | Degrees Celsius (°C) |
|---|---|
| 99 | 37.2222 |
| 100 | 37.7778 |
| 100.4 | 38 |
| 101 | 38.3333 |
| 102 | 38.8889 |
| 103 | 39.4444 |
| 104 | 40 |
| 105 | 40.5556 |
| 106 | 41.1111 |
| 107 | 41.6667 |
About These Scales
Degree Fahrenheit
On the Fahrenheit scale water freezes at 32 degrees and boils at 212 degrees, so one Fahrenheit degree is 5/9 the size of a Celsius degree. It remains the standard scale for weather, ovens and body temperature in the United States.
Degree Celsius
The Celsius scale puts the freezing point of water at 0 degrees and its boiling point at 100 degrees at sea level. It is the everyday temperature scale in nearly every country except the United States.
Definitions follow The SI Brochure, BIPM. See how we calculate for the exact values and rounding rules.
Frequently Asked Questions
Is 103 °F serious?
It is a high fever. US guidance generally advises adults to contact a doctor at or above 103 °F, and sooner for children, older adults, or anyone with symptoms such as confusion or difficulty breathing.
What is 104 °F in Celsius?
104 °F is exactly 40 °C, the point at which a fever needs medical attention.
What is 105 °F in Celsius?
105 °F is 40.5556 °C, which warrants urgent medical attention.
Does a higher fever mean a worse illness?
Not reliably. How ill someone is, and which other symptoms are present, tell you more than the height of the fever alone.