Transparent method
The formula
Worked example
Example inputs
How to interpret the result
Kelvin has no negative values at all, because zero Kelvin represents absolute zero, the physical limit past which temperature simply cannot go, unlike Celsius and Fahrenheit, whose zero points are arbitrary reference marks that allow negative readings on either side.
Before you rely on it
What to check
Expect only positive values in a Kelvin conversion. A negative Kelvin result signals an input or formula error, not a valid physical temperature.
The common error
Where people go wrong with temperature converter calculator
Treating Kelvin's zero point as arbitrary the way Celsius and Fahrenheit's are. Kelvin's zero is a genuine physical floor, and a converted value coming out negative means something upstream went wrong.
Sensitivity evidence
How value changes the converted value
| Value | Converted value | Difference from freezing (0°C / 32°F) |
|---|---|---|
| 79 | 26.1 | 26.1 |
| 89 | 31.7 | 31.7 |
| 99 | 37.2 | 37.2 |
| 108 | 42.2 | 42.2 |
| 118 | 47.8 | 47.8 |
Every input, tested
Which input moves the converted value most
| Input | Tested from | To | Converted value at each end | Swing |
|---|---|---|---|---|
| From | Celsius | Kelvin | 98.6 to -174.5 | 273.2 (738%) |
| To | Celsius | Kelvin | 37 to 310.2 | 273.2 (738%) |
| Value | 89 | 108 | 31.7 to 42.2 | 10.6 (29%) |
Step by step
The worked example, input by input
| Input | Value used | What it means |
|---|---|---|
| Value | 98.6 | |
| From | Fahrenheit | Unit to convert from. |
| To | Celsius | Unit to convert to. |
| Converted value | 37 | |
| Difference from freezing (0°C / 32°F) | 37 | |
Inputs, definitions and assumptions
Value
From
Unit to convert from.
To
Unit to convert to.
Where the inputs come from
Enter the temperature and choose the scales to convert between: Celsius, Fahrenheit and Kelvin. The conversion passes through Celsius, using F equals C times 9 over 5 plus 32 and K equals C plus 273.15. Read the temperature from a thermometer or a recipe and keep the unit it was given in. For a temperature difference rather than a reading, the offsets do not apply, and only the scale factor matters.
When the result stops applying
Kelvin has no degree symbol and cannot be negative. Rounding matters for scientific work, and recipes and weather reports round. Precision beyond what the thermometer measures is not meaningful. Body temperature, oven settings and weather each use a narrow range, so a converted value that looks odd, such as 400 degrees Celsius for a home oven, is a sign the scale was mixed up. Round to the precision the task needs: whole degrees for weather, five-degree steps for an oven and tenths for a fever reading.
What to compare it with
See wind chill and heat index on the weather calculators, dew point on the dew point page, and degree days on the degree days calculator. The combined gas law calculator needs temperatures in Kelvin, and the energy converter covers heat units.
People also ask
Frequently asked questions
How do I convert Fahrenheit to Celsius?
Subtract 32 and multiply by 5 over 9. So 98.6 Fahrenheit is 37 Celsius.
What is absolute zero?
0 Kelvin, or minus 273.15 Celsius, the lowest possible temperature, at which particles have minimal motion.
Why do scientists use Kelvin?
Because it starts at absolute zero, so temperatures are proportional to energy and formulas such as the gas laws work directly.