Convert between Celsius, Fahrenheit and Kelvin.
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How do you convert between Celsius, Fahrenheit and Kelvin?
Use °F = °C × 9/5 + 32, °C = (°F − 32) × 5/9, and K = °C + 273.15. These are offset conversions, not simple ratios. For example, 100 °C = 212 °F = 373.15 K, the boiling point of water at sea level. Celsius and Kelvin share the same step size, but Kelvin starts at absolute zero.
Understanding your result
Celsius and Kelvin share the same step size but Kelvin starts at absolute zero. Fahrenheit uses a different zero and a smaller degree.
Formula and method
°F = °C × 9/5 + 32; °C = (°F − 32) × 5/9; K = °C + 273.15. These are offset conversions, not simple ratios.
Assumptions and limitations
Temperature conversion is not a simple multiplication because the scales have different zero points, so the tool applies the full formulas (for example F = C x 9/5 + 32). Results are rounded to two decimals for display. Kelvin values below absolute zero (0 K, or -273.15 C) are not physically meaningful and should be treated as input errors.
Worked example
100 °C = 212 °F = 373.15 K (the boiling point of water at sea level).
Common temperature conversions
| Celsius | Fahrenheit | Kelvin |
|---|---|---|
| 0 °C | 32 °F | 273.15 K |
| 10 °C | 50 °F | 283.15 K |
| 20 °C | 68 °F | 293.15 K |
| 25 °C | 77 °F | 298.15 K |
| 30 °C | 86 °F | 303.15 K |
| 37 °C | 98.6 °F | 310.15 K |
| 37.8 °C | 100.04 °F | 310.95 K |
| 40 °C | 104 °F | 313.15 K |
| 50 °C | 122 °F | 323.15 K |
| 100 °C | 212 °F | 373.15 K |
| -40 °C | -40 °F | 233.15 K |
| -17.78 °C | 0 °F | 255.37 K |
How to use this tool
- Enter the temperature.
- Choose the scale to convert from and to.
- Read the result and all three scales.
Common mistakes to avoid
- Forgetting the +32 offset when converting Celsius to Fahrenheit.
About the Temperature Converter
Convert a temperature between Celsius, Fahrenheit and Kelvin. Enter a value and see all three scales at once.
Who should use this tool
Anyone reading temperatures in an unfamiliar scale — travellers converting weather forecasts between Celsius and Fahrenheit, cooks following recipes written for another country's ovens, students working through science problems in Kelvin, and health users interpreting a body-temperature reading. It covers Celsius, Fahrenheit and the absolute Kelvin scale.
Benefits
- Applies the correct offset formulas, not an approximate ratio
- Shows Celsius, Fahrenheit and Kelvin together for instant cross-reference
- Handles negative temperatures and the absolute Kelvin scale correctly
- Works offline, so it is handy for travel without a data connection
Practical use cases
- Converting a weather forecast between Celsius and Fahrenheit while travelling
- Adjusting an oven setting when a recipe uses the other temperature scale
- Solving physics and chemistry problems that require Kelvin
- Checking whether a body-temperature reading indicates a fever
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Frequently asked questions
What is 100°C in Fahrenheit?
100 °C equals 212 °F, the boiling point of water.
What is normal body temperature?
About 37 °C, which is 98.6 °F.
How do I convert Celsius to Fahrenheit?
Multiply the Celsius value by 9/5 (1.8) and add 32. For example, 20 C becomes 20 x 1.8 + 32 = 68 F. Water freezes at 0 C (32 F) and boils at 100 C (212 F).
What is normal body temperature in Fahrenheit?
The commonly cited average is 98.6 F, which is 37 C. Normal readings vary roughly from 97 to 99 F (36.1 to 37.2 C) depending on the person, time of day and measurement method.