Temperature Converter
To convert Celsius to Fahrenheit, multiply by 9/5 and add 32: 20 °C is 68 °F. To go from Fahrenheit to Celsius, subtract 32 and multiply by 5/9. Kelvin is Celsius plus 273.15. This converter applies these exact formulas between all three scales as you type.
°F = °C × 9/5 + 32 and K = °C + 273.15
How to use the Temperature Converter
- Type a temperature in the From box. It starts at 21 °C.
- Choose the From and To scales: Celsius, Fahrenheit or Kelvin.
- Read the result in the To box, or type there to convert the other way.
- Use the swap button to reverse the scales, and the chips to see the same temperature on the other scales.
Formula
°F = °C × 9/5 + 32 · °C = (°F - 32) × 5/9 · K = °C + 273.15Celsius and Kelvin use the same degree size with a 273.15 offset. A Fahrenheit degree is 5/9 the size of a Celsius degree, and the scales are offset by 32 degrees at the freezing point of water.
Temperature reference points
- Absolute zero: -273.15 °C = -459.67 °F = 0 K
- Water freezes: 0 °C = 32 °F = 273.15 K
- Room temperature: 20 to 22 °C = 68 to 72 °F
- Body temperature: 37 °C = 98.6 °F
- Water boils at sea level: 100 °C = 212 °F = 373.15 K
- Moderate oven: 180 °C = 356 °F (recipes often round to 350 °F)
The three scales
Celsius sets water freezing at 0 and boiling at 100 and is used almost everywhere. Fahrenheit sets them at 32 and 212 and is used mainly in the United States. Kelvin is the SI absolute scale: it starts at absolute zero, has no negative values and is written without a degree sign.
Temperature Converter questions
How do I convert Celsius to Fahrenheit?
Multiply the Celsius value by 9/5 (1.8) and add 32. For example, 20 °C × 1.8 + 32 = 68 °F. A quick mental estimate is to double the Celsius value and add 30, which gives 70 °F for 20 °C, close enough for weather but not for baking.
How do I convert Fahrenheit to Celsius?
Subtract 32 from the Fahrenheit value and multiply by 5/9. For example, (68 - 32) × 5/9 = 20 °C. For a rough estimate, subtract 30 and halve the result. Use the exact formula for cooking and medical temperatures. Body temperature of 98.6 °F works out to exactly 37 °C.
When should I use Kelvin instead of Celsius?
Use Kelvin for science and engineering calculations where absolute temperature matters, such as gas laws and thermodynamics. Kelvin starts at absolute zero (-273.15 °C), so it never goes negative. A change of 1 K is the same size as a change of 1 °C.
What oven temperatures match common recipe settings?
Common pairs are 150 °C for 300 °F, 175 to 180 °C for 350 °F, 190 °C for 375 °F, 200 °C for 400 °F, 220 °C for 425 °F and 230 °C for 450 °F. Fan ovens usually need about 20 °C less than conventional ovens.
How do I convert negative temperatures?
Use the same formulas and keep track of the sign. -10 °C × 1.8 + 32 = 14 °F, and (-10 °F - 32) × 5/9 = -23.3 °C. At -40 the Celsius and Fahrenheit scales meet: -40 °C equals -40 °F.
What temperatures matter for food safety?
Keep the fridge at 4 °C (40 °F) or below and the freezer at -18 °C (0 °F). Bacteria grow fastest between 4 and 60 °C (40 to 140 °F). Cook poultry to 74 °C (165 °F), ground meat to 71 °C (160 °F) and whole cuts of beef to 63 °C (145 °F).
What weather temperatures feel comfortable in each scale?
Most people find 18 to 24 °C (64 to 75 °F) comfortable. 30 °C (86 °F) is a hot day, 10 °C (50 °F) is cool, 0 °C (32 °F) is freezing and 40 °C (104 °F) is dangerous heat. These anchors help when reading forecasts abroad.