Temperature Converter
Convert temperature scales with the formula behind each answer. Scales with different zero points cannot be converted with a single factor.
0 °C = 32 °F (scales with different zero points need a formula, not one factor)
Common conversions
- °F = °C × 9/5 + 32
- °C = (°F − 32) × 5/9
- K = °C + 273.15
- °C = K − 273.15
Why there is no single factor
Celsius and Fahrenheit start at different zero points, so converting needs an offset as well as a scale: °F = °C × 9/5 + 32. Kelvin has the same degree size as Celsius with the zero moved to absolute zero.
Temperature differences
A change of 10 °C is a change of 18 °F, with no 32-degree offset, because the offset cancels in a difference. Cable derating tables use a difference from the reference ambient, so convert the temperatures first and then subtract.
Cable and insulation ratings
Conductor temperature ratings such as 70 °C for PVC and 90 °C for XLPE are limits on the conductor, and the ambient temperature changes the current a cable may carry. The cable derating calculator applies the correction factors.
Formulas
Scales and reference points
| Unit | Reference point | What it is |
|---|---|---|
| K | Base unit. 0 K is absolute zero | Kelvin, the SI unit of temperature. Zero is absolute zero. |
| °C | 0 °C = 273.15 K | Degree Celsius. 0 °C is the freezing point of water at standard pressure; the size of a degree equals one kelvin. |
| °F | 32 °F = 273.15 K | Degree Fahrenheit. A Fahrenheit degree is 5/9 of a kelvin. |
| °R | 0 °R = 0 K, 1 °R = 5/9 K | Degree Rankine: the Fahrenheit-sized degree on an absolute scale. |
Conversion pages
Frequently asked questions
What is the formula to convert °C to °F?
°F = °C × 9/5 + 32. For example, 100 °C is 212 °F.
How do I convert °F back to °C?
°C = (°F − 32) × 5/9. The Swap button above reverses the direction for any pair of units.
Is a change of 1 °C the same as a change of 1 °F?
No. One degree Celsius is 1.8 degrees Fahrenheit. A temperature difference converts with the 9/5 factor only, without the 32-degree offset.
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