Quick Overview
- 4 temperature units supported: Celsius, Fahrenheit, Kelvin, Rankine
- 12 conversion directions in one tool
- Formulas and step-by-step calculation explanations included
- Absolute zero validation: alerts for invalid Kelvin/Rankine values
- Suitable for scientific and everyday use
- Free, ad-free, no registration required
Temperature Converter: Celsius, Fahrenheit, Kelvin and Rankine
Use the tool above to instantly convert between Celsius, Fahrenheit, Kelvin and Rankine. Select the conversion type, enter the value, and the result is calculated automatically.
A recipe says "heat to 375°F" but your oven shows Celsius. Or a science paper writes 310 K and you want to make sense of it in Celsius. Maybe you came across a Rankine value in an engineering calculation and have no idea what it means.
Temperature scales developed independently across different geographies and scientific disciplines over centuries. Converting between them is a common need in both daily life and professional settings.
What Are Temperature Units?
There are four widely used temperature units in the world. Each has its own reference points and areas of application.
Celsius (°C) — The Metric Standard
Defined by Anders Celsius in 1742, this scale uses the freezing (0°C) and boiling (100°C) points of water as references. The majority of the world, including Turkey, uses Celsius in daily life. It is the most common scale across meteorology, cooking, medicine, and industry.
Fahrenheit (°F) — America's Preferred Scale
Developed by Daniel Gabriel Fahrenheit in 1724, water freezes at 32°F and boils at 212°F on this scale. It is used today primarily in the United States, the Cayman Islands, and Belize. You'll encounter it in daily weather forecasts and American recipes.
Kelvin (K) — The Universal Language of Science
Defined by Lord Kelvin in the 19th century, this scale takes absolute zero (0 K) as its starting point. No degree symbol is used — just "K". It is the standard unit in physics, chemistry, astrophysics, and engineering calculations. It never goes negative, because nothing can be colder than absolute zero.
Rankine (°R) — The Absolute Scale of Engineering
Rankine is the Fahrenheit-system equivalent of Kelvin: it starts from absolute zero but uses Fahrenheit's degree intervals. 0 °R = 0 K = −273.15°C. It is used primarily in American aerospace, space engineering, and thermodynamic calculations.
Conversion Formulas
All formulas are mathematically interconnected. Differences in reference points form the basis of the calculations.
Celsius ↔ Fahrenheit
°F = (°C × 9/5) + 32
°C = (°F − 32) × 5/9
Celsius ↔ Kelvin
K = °C + 273.15
°C = K − 273.15
Fahrenheit ↔ Kelvin
K = (°F − 32) × 5/9 + 273.15
°F = (K − 273.15) × 9/5 + 32
Celsius ↔ Rankine
°R = (°C + 273.15) × 9/5
°C = °R × 5/9 − 273.15
Fahrenheit ↔ Rankine
°R = °F + 459.67
°F = °R − 459.67
Kelvin ↔ Rankine
°R = K × 9/5
K = °R × 5/9
Key Reference Points
Point | Celsius | Fahrenheit | Kelvin | Rankine |
|---|---|---|---|---|
Absolute zero | −273.15°C | −459.67°F | 0 K | 0 °R |
Freezing point of water | 0°C | 32°F | 273.15 K | 491.67 °R |
Normal body temperature | 37°C | 98.6°F | 310.15 K | 558.27 °R |
Boiling point of water | 100°C | 212°F | 373.15 K | 671.67 °R |
Room temperature | 20–22°C | 68–71.6°F | 293–295 K | 527–531 °R |
Surface of the Sun | ~5,500°C | ~9,932°F | ~5,773 K | ~10,392 °R |
Which Scale Is Used Where?
Daily life: Turkey, Europe, Asia, Africa, Australia → Celsius. USA → Fahrenheit.
Meteorology: Global weather forecast models use Celsius and Kelvin. American weather services broadcast in Fahrenheit.
Medicine and health: In Turkey, body temperature is measured in Celsius (normal: 36.5–37.5°C). In the US, 98.6°F is the reference.
Science and research: The global physics, chemistry, and astrophysics community uses the Kelvin standard. Laws of thermodynamics are expressed in Kelvin.
Engineering: American engineering standards (ASME, NASA) use Rankine. European and global standards prefer Kelvin.
Cooking: Recipes are usually given in Celsius or Fahrenheit. A Turkish user who sees "375°F" needs to calculate that it's approximately 190°C.
Why Is Using a Tool Better Than Manual Calculation?
Manual calculation is possible, but the margin of error is high. Especially in chained conversions — for example, from Rankine to Celsius and then to Fahrenheit — rounding errors accumulate at each step. In an industrial furnace calibration or a drug storage temperature, that difference can be critical. The tool always calculates using the exact formula, with 2 decimal precision.