Temperature Converter
Convert between Celsius, Fahrenheit, Kelvin, and Rankine instantly.
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How to use this calculator
- 1
Enter the temperature value in the "From" field.
- 2
Select the scale you are converting from (e.g. Celsius).
- 3
Select the scale you want to convert to (e.g. Fahrenheit).
- 4
The result appears instantly. Both fields are editable — you can type in either.
Frequently asked questions
Which temperature scales are supported?
Celsius, Fahrenheit, Kelvin and Rankine. Kelvin is used as the base internally, so each pair goes through an absolute scale.
What are the exact formulas?
Fahrenheit = Celsius × 9/5 + 32, and Celsius = (Fahrenheit − 32) × 5/9. Kelvin = Celsius + 273.15, and Rankine = Kelvin × 9/5. For example, 37 °C is 98.6 °F, and 350 °F is 176.6666667 °C.
At what temperature do Celsius and Fahrenheit agree?
At −40. Setting C = F in the conversion formula gives −40 °C = −40 °F, which the tool confirms. Kelvin and Rankine values at that point are 233.15 K and 419.67 °R.
What is absolute zero on each scale?
Absolute zero is 0 K, which equals −273.15 °C, −459.67 °F and 0 °R. The Kelvin and Rankine scales start there. The converter does not block you from typing values below it, but they have no physical meaning.
Why is Kelvin written without a degree sign?
Kelvin is an absolute scale and an SI base unit, so the symbol is just K. Since 2019 the kelvin has been defined by fixing the Boltzmann constant at 1.380649 × 10⁻²³ J/K. A Kelvin step has the same size as a Celsius step; only the zero point differs.
Does the converter handle temperature differences?
No. It converts readings, which have an offset. A rise of 10 °C is a rise of 18 °F, not 50 °F, because differences scale by 9/5 without the 32 degree shift. Use the scale factor alone when you are comparing changes.
Why do I see numbers like 80.33 or 255.3722222?
Exact fractions such as 5/9 do not terminate, so results are shown to about ten significant digits. 0 °F is 255.3722222 K, and 300 K is 26.85 °C or 80.33 °F. For cooking or weather, round to whole degrees.
What does Rankine have to do with Fahrenheit?
Rankine uses Fahrenheit-sized degrees but starts at absolute zero, so °R = °F + 459.67. It is used in some US thermodynamics work, which is why 32 °F is 491.67 °R.
Temperature scale conversion: Celsius, Fahrenheit, Kelvin and Rankine
Offsets and scale factors
Most unit conversions multiply by a single number, but temperature scales have different zero points as well as different step sizes. Celsius and Kelvin share a step but differ by 273.15. Fahrenheit and Rankine share a step that is 5/9 the size of a Celsius degree, and Rankine starts at absolute zero. That is why each conversion needs an offset plus a ratio.
| Celsius | Fahrenheit | Kelvin | Rankine |
|---|---|---|---|
| −40 °C | −40 °F | 233.15 K | 419.67 °R |
| 0 °C | 32 °F | 273.15 K | 491.67 °R |
| 20 °C | 68 °F | 293.15 K | 527.67 °R |
| 37 °C | 98.6 °F | 310.15 K | 558.27 °R |
| 100 °C | 212 °F | 373.15 K | 671.67 °R |
Worked example: oven and weather temperatures
A recipe calling for 350 °F is 176.6666667 °C, close to the 180 °C setting on a metric oven. A comfortable room at 20 °C reads 68 °F, and a body temperature of 98.6 °F converts back to exactly 37 °C.
Worked example: absolute scales
A reading of 300 K is 26.85 °C and 80.33 °F. At the cold extreme, 0 °F equals 255.3722222 K, and −273.15 °C is 0 K. Scientific data sheets and gas law calculations require Kelvin, because ratios of temperature are only meaningful on an absolute scale.
Common mistakes
Do not double a Celsius number to estimate Fahrenheit without adding 32, and never treat a temperature change like a temperature reading. Rounding the intermediate result can also push a freezing point just above or below 0 °C. When accuracy matters, keep the full digits through the calculation and round only the final answer. As a sanity check, remember two anchors: water freezes at 0 °C (32 °F) and boils at 100 °C (212 °F) at standard atmospheric pressure, and every 5 °C step corresponds to 9 °F.
Using the converter for science and daily life
For forecasts and cooking, a whole degree is enough, so read 26.85 °C as about 27 °C. For physics and chemistry, convert to Kelvin before using gas laws or radiation formulas, since they need absolute temperature. Either box can be edited, so you can type a Fahrenheit value and read Celsius without touching the dropdowns. Keep in mind that the tool changes readings, not intervals, and it applies no limit at absolute zero.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →