Temperature Converter
°F = °C × 9/5 + 32 · K = °C + 273.15
TemperatureHow to Use This Tool
Temperature Conversion Formulas
Unlike length and weight conversions, temperature conversions are non-linear — they involve both a scale change and an offset. This means you cannot simply multiply by a factor; the formula must be applied correctly.
The Four Temperature Scales
- Celsius (°C): water freezes at 0°C, boils at 100°C. Used worldwide.
- Fahrenheit (°F): water freezes at 32°F, boils at 212°F. Used in the US.
- Kelvin (K): absolute zero is 0 K (-273.15°C). The SI unit of temperature.
- Rankine (°R): absolute zero is 0°R. Like Kelvin but with Fahrenheit-sized degrees.
Conversion Formulas
| From | To | Formula |
|---|---|---|
| °C | °F | °F = °C × 9/5 + 32 |
| °F | °C | °C = (°F − 32) × 5/9 |
| °C | K | K = °C + 273.15 |
| K | °C | °C = K − 273.15 |
| °F | °R | °R = °F + 459.67 |
Common Reference Points
| Reference | °C | °F | K |
|---|---|---|---|
| Absolute zero | -273.15 | -459.67 | 0 |
| Water freezes | 0 | 32 | 273.15 |
| Room temperature | 20 | 68 | 293.15 |
| Body temperature | 37 | 98.6 | 310.15 |
| Water boils | 100 | 212 | 373.15 |
Formula & Explanation
Temperature conversions are non-linear because the Fahrenheit and Celsius scales have different zero points. Use the formulas above rather than a simple multiplication factor.
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Frequently Asked Questions
How do I convert Celsius to Fahrenheit?
To convert Celsius to Fahrenheit, multiply the Celsius value by 9/5 (or 1.8) and add 32. The formula is: u00b0F = (u00b0C u00d7 9/5) + 32. For example, 20u00b0C = (20 u00d7 1.8) + 32 = 68u00b0F.
How do I convert Fahrenheit to Celsius?
To convert Fahrenheit to Celsius, subtract 32 from the Fahrenheit value and multiply by 5/9. The formula is: u00b0C = (u00b0F u2212 32) u00d7 5/9. For example, 98.6u00b0F = (98.6 u2212 32) u00d7 5/9 = 37u00b0C.
What is absolute zero in different scales?
Absolute zero is the lowest possible temperature, where all thermal motion stops. It equals 0 K (Kelvin), -273.15u00b0C (Celsius), -459.67u00b0F (Fahrenheit), and 0u00b0R (Rankine).
Why is there no 'degree' symbol for Kelvin?
By international convention, Kelvin temperatures are written without the degree symbol (e.g., 273 K, not 273u00b0K). This is because Kelvin is an absolute scale, while Celsius and Fahrenheit are relative scales.
What's the difference between Rankine and Kelvin?
Both Rankine and Kelvin are absolute temperature scales (starting at absolute zero). The difference is the size of the degree: one Kelvin degree equals one Celsius degree, while one Rankine degree equals one Fahrenheit degree. 1 K = 1.8 u00b0R.