How it works
This temperature converter switches between Celsius, Fahrenheit and Kelvin as you type. Temperature scales use different zero points and intervals. Celsius sets 0 degrees at water's freezing point and 100 degrees at boiling. Fahrenheit uses 32 and 212 for the same points. Kelvin starts at absolute zero (minus 273.15 Celsius), the coldest possible temperature, and uses the same interval size as Celsius.
The conversion formulas are: F = C times 9/5 plus 32, and K = C plus 273.15. Rearranging these gives the inverse conversions. This tool applies all three formulas live as you type in any field.
Temperature conversion is exact arithmetic. Only the display is rounded to two decimal places.
How do I convert Celsius to Fahrenheit and Kelvin?
To convert Celsius to Fahrenheit, multiply by 9/5 and add 32; to convert Celsius to Kelvin, add 273.15. Example: 37C (body temperature) equals 37 x 9/5 + 32 = 98.6F and 37 + 273.15 = 310.15 K.
Steps to convert between Celsius, Fahrenheit, and Kelvin
- To convert Celsius to Fahrenheit, multiply the Celsius value by 9/5 (or 1.8), then add 32.
- To convert Fahrenheit to Celsius, subtract 32 from the Fahrenheit value, then multiply by 5/9.
- To convert Celsius to Kelvin, add 273.15 to the Celsius value; to reverse it, subtract 273.15 from Kelvin.
- To convert Fahrenheit to Kelvin, first convert Fahrenheit to Celsius, then add 273.15.
- Round the final result to the number of decimal places needed; this tool shows two decimal places.
Temperature conversion formulas
F = C x 9/5 + 32 · K = C + 273.15 · C = (F - 32) x 5/9 · C = K - 273.15
- C = temperature in degrees Celsius
- F = temperature in degrees Fahrenheit
- K = temperature in Kelvin, an absolute scale written without a degree symbol
Common temperature conversions
What is 100°F in Celsius?
100°F is 37.8°C. Subtract 32, then multiply by 5/9: (100 − 32) × 5/9 = 37.8°C.
What is 0°C in Fahrenheit?
0°C, the freezing point of water, is 32°F: 0 × 9/5 + 32 = 32°F.
What is 36.6°C in Fahrenheit?
36.6°C, a typical human body temperature, is 97.9°F: 36.6 × 9/5 + 32 = 97.9°F.
What is 180°C in Fahrenheit?
180°C, a common oven setting, is 356°F: 180 × 9/5 + 32 = 356°F.
What is 350°F in Celsius?
350°F, a common baking temperature, is 176.7°C: (350 − 32) × 5/9 = 176.7°C.
What temperature is the same number in Celsius and Fahrenheit?
-40 degrees. -40°C equals -40°F, the only point where the two scales show the same number.
What is 25°C in Fahrenheit?
25°C, a typical room temperature, is 77°F: 25 × 9/5 + 32 = 77°F.
What is 98.6°F in Celsius?
98.6°F, the traditional average body temperature, is 37°C: (98.6 − 32) × 5/9 = 37°C.
Example temperatures in all three scales
| Celsius | Fahrenheit | Kelvin | Reference point |
|---|
| 0 C | 32 F | 273.15 K | Water freezes |
| 37 C | 98.6 F | 310.15 K | Human body temperature |
| 100 C | 212 F | 373.15 K | Water boils (sea level) |
| -40 C | -40 F | 233.15 K | Celsius and Fahrenheit meet |
| 25 C | 77 F | 298.15 K | Room temperature |
Frequently asked questions
Why do Celsius and Fahrenheit both equal -40 at the same point?
The formula F = C x 9/5 + 32 crosses the line F = C at exactly -40, because -40 x 9/5 + 32 = -40. It is the one temperature where both scales show the same number.
Why does Kelvin never go below zero?
Kelvin is an absolute scale starting at absolute zero, the theoretical point where atomic motion is minimal, equal to -273.15C. Since nothing can be colder than absolute zero, Kelvin values are never negative.
Is Kelvin written with a degree symbol?
No. By SI convention, Kelvin values are written as 310.15 K without a degree symbol, unlike Celsius (C) and Fahrenheit (F), because Kelvin is defined as an absolute unit rather than a relative degree scale.
How accurate is this converter?
The conversion formulas are exact; only the displayed result is rounded, to two decimal places in this tool. For scientific work requiring more precision, use the exact fractions (9/5 and 5/9) rather than decimal approximations.
This tool performs exact linear conversion between Celsius, Fahrenheit, and Kelvin; it does not account for other historical scales such as Rankine or Reaumur.
Sources: NIST Special Publication 811 - Guide for the Use of the International System of Units (SI)