Celsius to Fahrenheit Converter

Convert temperatures between Celsius, Fahrenheit, and Kelvin instantly. Essential tool for cooking, science, weather, and travel.

°C
Enter temperature in degrees Celsius
°F
Enter temperature in degrees Fahrenheit
-40°C / -40°F 0°C / 32°F 20°C / 68°F 37°C / 98.6°F 100°C / 212°F
Extreme Cold
Water Freezes
Cool Day
Room Temp
Warm Day
Body Temp
Water Boils
Absolute Zero
Conversion Result
20°C = 68°F
Celsius
20 °C
Degrees Celsius °C
Fahrenheit
68 °F
Degrees Fahrenheit °F
Kelvin
293.15 K
Kelvin K
Equivalent Temperatures
20°C
Celsius
68°F
Fahrenheit
293.15K
Kelvin
527.67°R
Rankine
Temperature Scale Comparison

Conversion Formulas:

°F = (°C × 9/5) + 32

°C = (°F - 32) × 5/9

Calculation: (20°C × 9/5) + 32 = 68°F

Understanding Temperature Scales

Celsius (°C) is the most widely used temperature scale worldwide. It was developed by Anders Celsius in 1742. The Celsius scale sets the freezing point of water at 0°C and the boiling point at 100°C at standard atmospheric pressure.

Fahrenheit (°F) is a temperature scale used primarily in the United States. It was proposed by Daniel Gabriel Fahrenheit in 1724. On this scale, the freezing point of water is 32°F and the boiling point is 212°F at standard atmospheric pressure.

Celsius Scale Characteristics:

  • Proposed by Anders Celsius (1701-1744)
  • Originally had 0°C as boiling point and 100°C as freezing point (later reversed)
  • Used by most countries worldwide and in scientific contexts
  • Part of the International System of Units (SI)
  • Simple relationship with Kelvin: K = °C + 273.15

Fahrenheit Scale Characteristics:

  • Proposed by Daniel Gabriel Fahrenheit (1686-1736)
  • 0°F was based on the freezing point of brine
  • 96°F was originally set as human body temperature (later adjusted to 98.6°F)
  • Primary use: United States, Cayman Islands, Belize
  • Commonly used in weather reports in the US

Temperature Scale Conversions

Scale Freezing Point (Water) Boiling Point (Water) Absolute Zero Human Body Temperature
Celsius (°C) °C 0°C 100°C -273.15°C 37°C
Fahrenheit (°F) °F 32°F 212°F -459.67°F 98.6°F
Kelvin (K) K 273.15 K 373.15 K 0 K 310.15 K
Rankine (°R) 491.67°R 671.67°R 0°R 558.27°R

Temperature Unit Conversions

From To Formula Example
Celsius Fahrenheit °F = (°C × 9/5) + 32 20°C = (20×9/5)+32 = 68°F
Fahrenheit Celsius °C = (°F - 32) × 5/9 68°F = (68-32)×5/9 = 20°C
Celsius Kelvin K = °C + 273.15 20°C = 20+273.15 = 293.15K
Fahrenheit Kelvin K = (°F - 32) × 5/9 + 273.15 68°F = (68-32)×5/9+273.15 = 293.15K
Celsius Rankine °R = (°C × 9/5) + 491.67 20°C = (20×9/5)+491.67 = 527.67°R

Practical Applications

1

International Travel: Most countries use Celsius for weather reports, while the US uses Fahrenheit. When traveling from Celsius-using countries to the US, conversion is essential. For example, a pleasant 20°C day in Europe is 68°F in the US.

2

International Cooking: Recipes from different countries specify oven temperatures in Celsius or Fahrenheit. European recipes typically use Celsius, while American recipes use Fahrenheit. A common conversion is 180°C = 356°F for baking. Home cooks need to convert between scales when trying international recipes.

3

Scientific and Medical Fields: Celsius is used in most scientific contexts as part of the SI system. However, the US medical field often uses Fahrenheit for body temperature. Healthcare professionals must be able to convert between scales when reading international research or communicating with colleagues worldwide.

Common Temperature Conversions

Celsius (°C) Fahrenheit (°F) Kelvin (K) Description / Application
-273.15°C -459.67°F 0 K Absolute zero - theoretically lowest possible temperature
-40°C -40°F 233.15 K Temperature where Celsius and Fahrenheit scales intersect
-20°C -4°F 253.15 K Very cold winter day in northern regions
0°C 32°F 273.15 K Freezing point of water at sea level
10°C 50°F 283.15 K Cool spring or autumn day
20°C 68°F 293.15 K Comfortable room temperature
30°C 86°F 303.15 K Warm summer day
37°C 98.6°F 310.15 K Average human body temperature
40°C 104°F 313.15 K Very hot day, heat advisory conditions
100°C 212°F 373.15 K Boiling point of water at sea level
232.8°C 451°F 505.95 K Temperature at which paper ignites (Fahrenheit 451)

Calculator Features:

  • Bidirectional conversion: Celsius to Fahrenheit and vice versa
  • Interactive temperature slider for easy adjustment
  • Includes Kelvin and Rankine temperature scales
  • Temperature scale visualization
  • Common temperature examples for quick reference
  • Mobile-friendly interface with responsive design

Frequently Asked Questions

The Celsius and Fahrenheit scales intersect at -40° because the conversion formulas create an equation where C = F. Solving F = (9/5)C + 32 with F = C gives C = (9/5)C + 32, which simplifies to (-4/5)C = 32, resulting in C = -40. So -40°C = -40°F. This is the only temperature where the numerical values are equal on both scales.

Most countries adopted Celsius as part of the metric system during the 19th and 20th centuries because it's simpler and more logical. The Celsius scale is based on the properties of water (0°C freezing, 100°C boiling at sea level), making it intuitive for scientific and everyday use. Additionally, it integrates seamlessly with the Kelvin scale used in science. The metric system, including Celsius, was adopted internationally for standardization in trade, science, and communication.

Recent studies suggest that average human body temperature may be slightly lower than the traditional 37°C (98.6°F). A 2020 study found the average to be around 36.6°C (97.9°F). The original 37°C measurement came from 19th-century German physician Carl Reinhold August Wunderlich. Normal body temperature can vary by individual, time of day, age, and other factors, typically ranging from 36.1°C to 37.2°C (97°F to 99°F).

For a quick estimate: Double the Celsius temperature, then add 30. For example, 20°C × 2 = 40, 40 + 30 = 70°F (actual: 68°F). This method is accurate within a few degrees for typical weather temperatures. For more precision: Multiply Celsius by 9/5, then add 32. The reverse estimate: Subtract 30 from Fahrenheit, then divide by 2. Example: 68°F - 30 = 38, 38 ÷ 2 = 19°C (actual: 20°C).

Celsius and Centigrade refer to the same temperature scale. "Centigrade" means "divided into 100 degrees" (from Latin "centum" for 100 and "gradus" for step). The scale was officially renamed "Celsius" in 1948 to honor Anders Celsius and avoid confusion with other centigrade measurements. Today, "Celsius" is the preferred term, though "Centigrade" is still occasionally used, particularly by older generations.