104 degrees Fahrenheit = 40.00°C (313.15 K). Use the copy buttons below for any format, or enter a custom value in the converter.
Fahrenheit is the primary temperature scale in the United States, while Celsius is the international standard used by the rest of the world and all scientific disciplines. To convert Fahrenheit to Celsius, subtract 32 then multiply by 5/9: °C = (°F − 32) × 5/9. For 104°F: (104 − 32) × 5/9 = 40.00°C. Kelvin — used in science — adds 273.15 to the Celsius result: 40.00°C + 273.15 = 313.15 K.
104°F
40.00°C
313.15 K
Celsius
40.00°C
Kelvin
313.15 K
Full (°F to °C)
104°F = 40.00°C
Full (°F to K)
104°F = 313.15 K
High fever (40°C)
104°F (40°C) is a high fever requiring medical attention in adults, and an extreme outdoor air temperature seen during dangerous heat waves. Heat stroke risk rises sharply for vulnerable people at this level.
Enter any Fahrenheit value to convert it live to Celsius and Kelvin.
Three practical situations where knowing that 104°F = 40.00°C makes a real difference.
Cooking techniques like sous-vide, chocolate tempering, and yogurt fermentation often reference Fahrenheit temperatures in US recipe books. 104°F equals 40.00°C — useful to know when adapting a US recipe for a metric kitchen thermometer or instant-read probe.
If you're visiting the United States and a weather app shows 104°F, that means 40.00°C. Dress light and stay hydrated — it's going to be a hot day. US weather forecasts, thermostats, and ovens almost universally use Fahrenheit, so this conversion is essential for international visitors.
In physics or chemistry, temperatures are often given in Fahrenheit in US textbooks but need to be expressed in Celsius or Kelvin for formulas. 104°F = 40.00°C = 313.15 K. Kelvin is required for thermodynamic equations like the ideal gas law (PV = nRT) since it starts at absolute zero (0 K = −459.67°F). Converting 104°F: (104 − 32) × 5/9 + 273.15 = 313.15 K.
See how 104°F compares to nearby temperatures in both Fahrenheit and Celsius.
Common questions about 104°F and its Celsius equivalent, answered.