Temperature Converter
Type a value in any scale and read the other three instantly. Every conversion shows its formula with your own numbers, and anything below absolute zero is flagged as impossible
Enter a Temperature
Edit any field: the last one you touch is the source and the other three follow
Within the liquid range of water at 1 atm (0 °C to 100 °C).
Reference Temperatures
Tap any row to load it into the converter. Real-world values are approximate; definitions are exact.
| Reference Point | °C | °F | K |
|---|
How to use this tool
- Type a value in any of the four fields: Celsius, Fahrenheit, Kelvin or Rankine.
- The other three update immediately; the last field you touch is the source.
- Choose how many decimal places to show (0 to 4).
- Read the formulas with your own numbers, use the reference table of well-known temperatures, or copy the result.
Worked example
25 °C converts to 77 °F (25 × 9/5 + 32), 298.15 K (25 + 273.15) and 536.67 °R ((25 + 273.15) × 9/5). The two everyday scales meet at −40, because solving x = 9x/5 + 32 gives x = −40. Human body temperature is conventionally 37 °C = 98.6 °F, and a 350 °F oven setting is about 176.667 °C. Anything below absolute zero (0 K, −273.15 °C, −459.67 °F) is flagged as impossible, since the kelvin has no negative values. The conversions are exact by definition; real thermometers are only as accurate as their calibration.
Methodology
Every scale here is tied to the kelvin, so each conversion is a fixed offset, a fixed ratio, or both. There is no empirical table behind it and nothing that can go out of date.
Oven dial settings in three scales
US recipes give oven temperatures in Fahrenheit, most of the world sets dials in Celsius. Here are seven common settings converted by the tool (°C to one decimal, K to two).
| Fahrenheit | Celsius | Kelvin |
|---|---|---|
| 250 °F | 121.1 °C | 394.26 K |
| 300 °F | 148.9 °C | 422.04 K |
| 350 °F | 176.7 °C | 449.82 K |
| 375 °F | 190.6 °C | 463.71 K |
| 400 °F | 204.4 °C | 477.59 K |
| 425 °F | 218.3 °C | 491.48 K |
| 450 °F | 232.2 °C | 505.37 K |
Read across a row: 350 °F is 176.7 °C, not a round number, because the two scales do not line up in neat steps. Ovens only offer steps of their own, so set the dial to the nearest value it has and treat the difference as normal: a few degrees either way is well within how much a home oven swings while heating. Real ovens can also run hotter or cooler than their dial, so an oven thermometer tells you more than any conversion. The numbers here are exact by definition; the cooking result is not.
Frequently asked questions
How do I convert Celsius to Fahrenheit? ▼
Multiply the Celsius value by 9/5 (1.8) and add 32. For example, 25 °C × 1.8 = 45, plus 32 gives 77 °F. To go the other way, subtract 32 first and then multiply by 5/9.
Why is −40 the same in Celsius and Fahrenheit? ▼
Because the two scales are straight lines that cross exactly once. Setting x = 9x/5 + 32 gives x = −40, so −40 °C and −40 °F are the same temperature. At any other value the two numbers differ.
Can a temperature be lower than 0 Kelvin? ▼
No. 0 K is absolute zero, the point where a system has the least possible thermal energy, equal to −273.15 °C or −459.67 °F. This converter rejects anything below it instead of returning a meaningless number.
What is the Rankine scale and when is it used? ▼
Rankine counts Fahrenheit-sized degrees from absolute zero, so 0 °R equals −459.67 °F and 491.67 °R equals the freezing point of water. It appears mainly in certain US thermodynamics and engineering textbooks; elsewhere kelvin is the norm.
Why is it “kelvin” and not “degrees Kelvin”? ▼
In 1967 the 13th General Conference on Weights and Measures dropped the word degree for this unit. The name is the lowercase kelvin, the symbol is K without a degree sign, and only Celsius, Fahrenheit and Rankine keep the degree mark.
Does water always boil at 100 °C (212 °F)? ▼
Only at standard atmospheric pressure (1 atm, about sea level). Lower pressure at altitude lowers the boiling point, which is why high-altitude cooking takes longer. The 100 °C and 212 °F marks in this tool assume 1 atm.