Enter a temperature in Celsius, Fahrenheit or Kelvin and instantly see it in the other two scales — for weather, cooking, science and travel.
What Is a Temperature Converter?
A temperature converter translates between the three temperature scales: Celsius (used by most of the world for weather and cooking), Fahrenheit (used in the United States), and Kelvin (the scientific scale, which starts at absolute zero). The scales are related by simple formulas anchored at water’s freezing and boiling points: 0 °C = 32 °F = 273.15 K, and 100 °C = 212 °F = 373.15 K. A famous curiosity: −40 is the same number on both the Celsius and Fahrenheit scales.
How to Use
- Enter the temperature value.
- Choose the scale it is in.
- Click “Convert Temperature”.
- Read the value in all three scales.
Formula
Fahrenheit = Celsius × 9/5 + 32. Celsius = (Fahrenheit − 32) × 5/9. Kelvin = Celsius + 273.15.
Worked Example
100 °C (boiling water at sea level): Fahrenheit = 100 × 9/5 + 32 = 212.00 °F. Kelvin = 100 + 273.15 = 373.15 K.
How It Works, In Plain Words
Temperature is the odd one out among conversions, because the scales do not share a zero. A length conversion is a simple multiply, but Celsius and Fahrenheit start counting from different points, so the tool works through Celsius as its hub and uses an offset as well as a ratio. If you enter Fahrenheit, it first undoes the offset and the ratio — subtract 32, then multiply by 5/9 — to reach Celsius. If you enter Kelvin, it subtracts 273.15, because Kelvin is Celsius shifted so that zero sits at absolute zero. From Celsius, the other two follow: Fahrenheit is Celsius × 9/5 + 32, and Kelvin is Celsius + 273.15. The worked example walks through boiling water: 100 × 9/5 + 32 = 212.00 °F, and 100 + 273.15 = 373.15 K. Before showing anything, the tool checks the Celsius value against −273.15; anything lower is below absolute zero, so it explains that the temperature is physically impossible instead of printing nonsense. Every result is then shown to two decimal places, all three scales together.
Real-World Uses
First, the kitchen. Recipes cross the Atlantic in both directions, and an oven set by the wrong scale ruins dinner: the page’s own warning is that 180 °C is 356 °F, not 180 °F. Converting the recipe temperature here first means the dial matches the book. Second, travel and weather. A forecast in a Fahrenheit country means little to a Celsius traveller until it is translated; checking what the numbers feel like — anchored by the page’s reference points, freezing at 0 °C = 32 °F and body temperature at about 98.6 °F, which is 37 °C — tells you whether to pack for cold or heat. Third, school and lab work. Science uses Kelvin because it starts at absolute zero, and students meeting gas laws or thermodynamics have to move between Kelvin and the everyday scales without slipping on the 273.15 shift; this tool shows all three side by side so the relationship stays visible.
Benefits
- All three scales shown together
- Cooking conversions for recipes written in the other system
- Weather checks when travelling between Celsius and Fahrenheit countries
- The absolute-zero guard stops impossible Kelvin values
Features of Our Tool
- Instant results in your browser
- No sign-up, no download, 100% free
- Works on mobile, tablet and desktop
- Clear step-by-step explanation below the tool
- Private — your entries never leave your device.
Common Mistakes
- Using the length-style “multiply only” conversion — temperature needs the +32 offset for Fahrenheit, not just a ratio
- Setting an oven by the wrong scale (180 °C is 356 °F, not 180 °F)
- Forgetting Kelvin has no degree symbol and cannot go below zero
Common Mistakes to Avoid
The classic error is treating temperature like length: multiplying by a single ratio and forgetting the +32 offset, which the page’s list calls out directly. The scales have different zeros, so the offset is not optional. A second mistake is adding a degree symbol to Kelvin: Kelvin takes none — write 373.15 K, not 373.15 °K — because it is an absolute scale, not a relative one. Third, expect the −40 curiosity to work only once: −40 is where the two scales cross, not a shortcut for other values. Finally, remember the physical floor. Nothing can be colder than absolute zero, −273.15 °C, and the tool’s guard will refuse such entries rather than convert them; if it refuses yours, the number was impossible, not the tool broken.
FAQ
What is 100 °C in Fahrenheit?
212 °F — the boiling point of water at sea level.
What is normal body temperature in Fahrenheit?
About 98.6 °F, which is 37 °C.
At what temperature are Celsius and Fahrenheit equal?
−40: minus forty degrees Celsius equals minus forty degrees Fahrenheit.
How do I convert Celsius to Kelvin?
Add 273.15 — for example, 100 °C = 373.15 K.
Why does Kelvin start at absolute zero?
Kelvin is built for science: 0 K is absolute zero, the coldest possible temperature, where particles have minimal energy. There are no negative Kelvin values.
What is 0 °C in Kelvin and Fahrenheit?
0 °C = 273.15 K = 32 °F — the freezing point of water, and the anchor all three scales share on this page.
Why does the tool refuse temperatures below −273.15 °C?
Because −273.15 °C is absolute zero, the coldest possible temperature. Nothing can be colder, so instead of converting an impossible value the tool explains why it cannot.