100 degrees Fahrenheit = 37.78°C (310.93 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 100°F: (100 − 32) × 5/9 = 37.78°C. Kelvin — used in science — adds 273.15 to the Celsius result: 37.78°C + 273.15 = 310.93 K.
100°F
37.78°C
310.93 K
Celsius
37.78°C
Kelvin
310.93 K
Full (°F to °C)
100°F = 37.78°C
Full (°F to K)
100°F = 310.93 K
Low-grade fever / extreme heat day
100°F (37.8°C) straddles two meanings: as a body temperature it signals a low-grade fever, and as an air temperature it represents a scorching heat wave day — common in summer across the US Southwest.
Enter any Fahrenheit value to convert it live to Celsius and Kelvin.
Three practical situations where knowing that 100°F = 37.78°C makes a real difference.
Cooking techniques like sous-vide, chocolate tempering, and yogurt fermentation often reference Fahrenheit temperatures in US recipe books. 100°F equals 37.78°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 100°F, that means 37.78°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. 100°F = 37.78°C = 310.93 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 100°F: (100 − 32) × 5/9 + 273.15 = 310.93 K.
See how 100°F compares to nearby temperatures in both Fahrenheit and Celsius.
Common questions about 100°F and its Celsius equivalent, answered.