Convert Between Celsius, Fahrenheit & Kelvin Instantly
Fast, accurate, and free temperature conversion tool. Convert any temperature unit with precision and get instant results with conversion formulas.
Convert between Celsius (°C), Fahrenheit (°F), and Kelvin (K) with our easy-to-use temperature converter. Perfect for cooking, science, weather, and everyday use.
Advertisement
Most widely used worldwide. Water freezes at 0°C and boils at 100°C at standard pressure.
Common uses: Weather, cooking, science
Symbol: °C (degree Celsius)
Named after: Anders Celsius
Primary scale in the United States. Water freezes at 32°F and boils at 212°F at standard pressure.
Common uses: US weather, medical, HVAC
Symbol: °F (degree Fahrenheit)
Named after: Daniel Fahrenheit
SI unit for temperature. Absolute scale starting at absolute zero (0 K = -273.15°C).
Common uses: Scientific research, physics
Symbol: K (no degree symbol)
Named after: Lord Kelvin
Temperature conversion is the process of converting a temperature reading from one scale to another. The three most common temperature scales are Celsius (°C), Fahrenheit (°F), and Kelvin (K). Each scale has its own reference points and is used in different parts of the world and various scientific applications.
Understanding the formulas helps you convert temperatures manually when needed:
°F = (°C × 9/5) + 32
Example: 25°C = (25 × 9/5) + 32 = 77°F
°C = (°F - 32) × 5/9
Example: 77°F = (77 - 32) × 5/9 = 25°C
K = °C + 273.15
Example: 25°C = 25 + 273.15 = 298.15 K
°C = K - 273.15
Example: 298.15 K = 298.15 - 273.15 = 25°C
K = (°F - 32) × 5/9 + 273.15
Example: 77°F = (77 - 32) × 5/9 + 273.15 = 298.15 K
°F = (K - 273.15) × 9/5 + 32
Example: 298.15 K = (298.15 - 273.15) × 9/5 + 32 = 77°F
Follow these simple steps to convert any temperature:
| Celsius (°C) | Fahrenheit (°F) | Kelvin (K) | Context |
|---|---|---|---|
| -40°C | -40°F | 233.15 K | Extremely cold |
| 0°C | 32°F | 273.15 K | Water freezes |
| 10°C | 50°F | 283.15 K | Cool day |
| 20°C | 68°F | 293.15 K | Room temperature |
| 37°C | 98.6°F | 310.15 K | Human body temp |
| 100°C | 212°F | 373.15 K | Water boils |
For quick estimates without a calculator:
Double the Celsius value and add 30
Example: 20°C ≈ (20 × 2) + 30 = 70°F (actual: 68°F)
Subtract 30 and divide by 2
Example: 70°F ≈ (70 - 30) ÷ 2 = 20°C (actual: 21.1°C)
Understanding temperature conversion is essential in our globalized world. Whether you're cooking international recipes, traveling abroad, working in science or engineering, or simply checking the weather in another country, knowing how to convert between temperature scales helps you make informed decisions and avoid costly mistakes.
In scientific research, accurate temperature conversion is critical for reproducible experiments. In cooking, the wrong temperature can ruin a dish. In healthcare, proper temperature measurement can be a matter of life and death. That's why having a reliable temperature converter at your fingertips is invaluable.
Advertisement
To convert Celsius to Fahrenheit manually, multiply the Celsius temperature by 9/5 (or 1.8), then add 32. Formula: °F = (°C × 9/5) + 32. For example, 25°C = (25 × 9/5) + 32 = 77°F. This formula works for any Celsius value you need to convert.
Celsius and Fahrenheit are different temperature scales with different reference points. Celsius (°C) is based on water freezing at 0° and boiling at 100° at standard pressure. Fahrenheit (°F) has water freezing at 32° and boiling at 212°. Celsius is used in most countries worldwide and in scientific applications, while Fahrenheit is primarily used in the United States and some Caribbean nations.
To convert Fahrenheit to Celsius quickly, subtract 32 from the Fahrenheit temperature, then multiply by 5/9 (or 0.556). Formula: °C = (°F - 32) × 5/9. For example, 77°F = (77 - 32) × 5/9 = 25°C. For a quick mental estimate, subtract 30 and divide by 2, though this is less accurate.
Kelvin is the SI (International System of Units) base unit of temperature used primarily in scientific research, physics, chemistry, and engineering. It starts at absolute zero (0 K = -273.15°C), the coldest possible temperature where molecular motion ceases. Scientists prefer Kelvin because it's an absolute scale with no negative values, making calculations in thermodynamics and quantum physics more straightforward.
Yes! For quick estimates without a calculator: Celsius to Fahrenheit - double the Celsius value and add 30. For Fahrenheit to Celsius - subtract 30 and divide by 2. While these aren't perfectly accurate, they give close approximations useful for everyday situations like checking weather or cooking temperatures.
Celsius and Fahrenheit are equal at -40 degrees. This means -40°C = -40°F. This is the only point where both scales show the same numerical value, and it's a useful fact to remember. It occurs in extremely cold conditions, which is why this temperature is significant in polar regions and high-altitude environments.
Converting Kelvin to Celsius is simple: subtract 273.15 from the Kelvin temperature. Formula: °C = K - 273.15. For example, 300 K = 300 - 273.15 = 26.85°C. This is one of the easiest temperature conversions because it only requires a single subtraction operation with no multiplication or division.
The United States uses Fahrenheit due to historical reasons. When temperature scales were being standardized in the 18th and 19th centuries, the US had already adopted Fahrenheit, which was invented by Daniel Gabriel Fahrenheit in 1724. Switching to Celsius would require changing countless systems, regulations, educational materials, and deeply ingrained public habits, making it a costly and complex transition that has never been fully implemented despite attempts.
Explore more conversion calculators
Convert between meters, feet, inches, kilometers, miles, and other length units instantly.
Convert kilograms, pounds, ounces, grams, and other weight units with precision.
Convert seconds, minutes, hours, days, weeks, and other time units effortlessly.
Convert mph, km/h, m/s, knots, and other speed units for vehicles and travel.
Convert liters, gallons, milliliters, cups, and other volume units for cooking and science.
Convert square meters, acres, hectares, square feet, and other area measurements.
"Every calculation counts, so does every tree. Plant a tree, grow a future."
As we help you with your daily calculations, we encourage you to think about our planet. Small actions like reducing energy consumption, using digital tools instead of paper, and supporting renewable energy make a difference. Let's calculate wisely and live sustainably together.