Fahrenheit to Celsius Converter

Convert Fahrenheit to Celsius instantly. Accurate temperature conversion with formulas, comparison tables, and temperature-related science information.

°F
Enter temperature in degrees Fahrenheit
°C
Enter temperature in degrees Celsius
-40°F / -40°C 32°F / 0°C 68°F / 20°C 100°F / 37.8°C 120°F / 48.9°C
Extreme Cold
Water Freezes
Room Temp
Body Temp
Hot Day
Water Boils
Paper Burns
Absolute Zero
Conversion Result
68°F = 20°C
Fahrenheit
68 °F
Degrees Fahrenheit °F
Celsius
20 °C
Degrees Celsius °C
Kelvin
293.15 K
Kelvin K
Equivalent Temperatures
68°F
Fahrenheit
20°C
Celsius
293.15K
Kelvin
527.67°R
Rankine
Temperature Scale Comparison

Conversion Formulas:

°C = (°F - 32) × 5/9

°F = (°C × 9/5) + 32

Calculation: (68°F - 32) × 5/9 = 20°C

Understanding Temperature Scales

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 (°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 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

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)

Temperature Scale Conversions

Scale Freezing Point (Water) Boiling Point (Water) Absolute Zero Human Body Temperature
Fahrenheit (°F) °F 32°F 212°F -459.67°F 98.6°F
Celsius (°C) °C 0°C 100°C -273.15°C 37°C
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
Fahrenheit Celsius °C = (°F - 32) × 5/9 68°F = (68-32)×5/9 = 20°C
Celsius Fahrenheit °F = (°C × 9/5) + 32 20°C = (20×9/5)+32 = 68°F
Fahrenheit Kelvin K = (°F - 32) × 5/9 + 273.15 68°F = (68-32)×5/9+273.15 = 293.15K
Celsius Kelvin K = °C + 273.15 20°C = 20+273.15 = 293.15K
Fahrenheit Rankine °R = °F + 459.67 68°F = 68+459.67 = 527.67°R

Practical Applications

1

Weather Forecasting: Most countries use Celsius for weather reports, but the United States uses Fahrenheit. When traveling or consuming international media, conversion is essential. For example, a pleasant 20°C day in Europe is 68°F in the US.

2

Cooking and Baking: Recipes often specify oven temperatures in Fahrenheit or Celsius depending on the country of origin. A common conversion is 350°F = 177°C for baking. Professional chefs often need to convert between the two scales.

3

Scientific Research: Celsius is used in most scientific contexts as part of the SI system. However, some specialized fields in the US may still use Fahrenheit. Researchers must be able to convert between scales when comparing data or reading international studies.

Common Temperature Conversions

Fahrenheit (°F) Celsius (°C) Kelvin (K) Description / Application
-459.67°F -273.15°C 0 K Absolute zero - theoretically lowest possible temperature
-40°F -40°C 233.15 K Temperature where Fahrenheit and Celsius scales intersect
0°F -17.78°C 255.37 K Very cold winter day in northern regions
32°F 0°C 273.15 K Freezing point of water at sea level
50°F 10°C 283.15 K Cool spring or autumn day
68°F 20°C 293.15 K Comfortable room temperature
86°F 30°C 303.15 K Warm summer day
98.6°F 37°C 310.15 K Average human body temperature
100°F 37.78°C 310.93 K Very hot day, heat advisory conditions
212°F 100°C 373.15 K Boiling point of water at sea level
451°F 232.8°C 505.95 K Temperature at which paper ignites (Fahrenheit 451)

Calculator Features:

  • Bidirectional conversion: Fahrenheit to Celsius 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 Fahrenheit and Celsius scales intersect at -40° because the conversion formulas create an equation where F = C. 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°F = -40°C. This is the only temperature where the numerical values are equal on both scales.

The United States continues to use Fahrenheit primarily due to historical precedent and the cost of changing. The metric system (including Celsius) was legalized for use in the US in 1866, but widespread adoption didn't occur. Changing all weather reports, road signs, appliances, and educational materials would be expensive and face public resistance. However, scientific fields in the US generally use Celsius and the metric system.

Recent studies suggest that average human body temperature may be slightly lower than the traditional 98.6°F (37°C). A 2020 study found the average to be around 97.9°F (36.6°C). The original 98.6°F 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 97°F to 99°F (36.1°C to 37.2°C).

For a quick estimate: Subtract 30 from the Fahrenheit temperature, then divide by 2. For example, 70°F - 30 = 40, 40 ÷ 2 = 20°C (actual: 21.1°C). This method is accurate within a few degrees for typical weather temperatures. For more precision: Subtract 32, then multiply by 5/9. The reverse estimate: Double the Celsius temperature, then add 30. Example: 20°C × 2 = 40, 40 + 30 = 70°F (actual: 68°F).

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.