Temperature Converter (Celsius ↔ Fahrenheit ↔ Kelvin)

How to use the Temperature Converter

1. Type a number into the box for the temperature you know: Celsius (°C), Fahrenheit (°F) or Kelvin (K).
2. As you type, the other two boxes update, and the formula used appears below the result.
3. Check the chart below the converter for common values such as body temperature and oven settings.

Celsius to Fahrenheit Formulas

• Celsius → Fahrenheit: °F = °C × 9/5 + 32 (or °C × 1.8 + 32)
• Fahrenheit → Celsius: °C = (°F − 32) × 5/9
• Celsius → Kelvin: K = °C + 273.15
• Kelvin → Celsius: °C = K − 273.15

For example, 25°C is 25 × 1.8 + 32 = 77°F, and 100°F is (100 − 32) × 5/9 ≈ 37.8°C. The two scales meet at −40, so −40°C = −40°F.

A Quick Way to Estimate Fahrenheit in Your Head

If you don't have a calculator handy, "double the Celsius and add 30" gets you close to Fahrenheit, and "subtract 30 and halve it" gets you close to Celsius. For everyday weather (0–30°C) the estimate is off by only about 2–4 degrees, which is close enough to decide whether you need a jacket.

Body Temperature in Fahrenheit: When Is It a Fever?

Thermometers sold in the United States usually read in °F, while those in the UK, Canada and Australia usually read in °C. Normal adult body temperature is often given as 98.6°F (37°C), but healthy readings around 97–99°F (36.1–37.2°C) are common. A reading of 100.4°F (38°C) or higher is generally treated as a fever. Converting helps when you're reading a thermometer, medicine label or health advice written in the other scale. Readings vary with where you measure (mouth, ear, armpit or forehead), so contact a doctor or nurse if you're worried about symptoms.

Oven and Air Fryer Temperatures in Recipes

American recipes give oven temperatures in Fahrenheit, while British, Australian and many Canadian recipes use Celsius (and older UK recipes sometimes use gas marks). Common settings:

If you use a fan (convection) oven, recipes often suggest lowering the temperature by about 20°C (25°F). Home ovens often run hotter or cooler than the dial says, so keep an eye on your first batch and adjust.

Reading Weather Forecasts in Fahrenheit

The US reports weather in Fahrenheit, while the UK, Canada, Australia and most other countries use Celsius. If you're traveling or reading an American forecast, this chart gives you a quick feel for the numbers.