The Fahrenheit scale is primarily used in the United States, while the Celsius scale is adopted by nearly all other nations and the scientific community worldwide. This divergence means that understanding how to translate a Fahrenheit temperature into its Celsius equivalent is a practical skill for travel, international communication, or scientific contexts. The following method provides the exact process for converting a temperature from Fahrenheit to Celsius.
The Conversion Formula
The mathematical relationship for converting a temperature in degrees Fahrenheit (F) to degrees Celsius (C) is given by the formula: C = (F – 32) x 5/9. This equation establishes a direct path for the conversion.
The formula accounts for the two main differences between the scales. Subtracting 32 addresses the offset in their zero points, since water freezes at 32 degrees F but 0 degrees C. The subsequent multiplication by the fraction 5/9 corrects for the difference in the size of the degree unit. This ratio is derived because there are 180 Fahrenheit degrees between the freezing and boiling points of water, compared to 100 Celsius degrees, which simplifies to 5/9.
Step-by-Step Calculation
To convert a specific temperature, such as 68 degrees F, into Celsius, the formula is applied sequentially through three steps. First, eliminate the offset by subtracting 32 from the Fahrenheit value. For the example of 68 degrees F, this initial step yields 68 – 32 = 36.
Next, multiply this result by the numerator of the ratio, which is 5 (36 x 5 = 180). The final step involves dividing this result by the denominator, 9. The division, 180 divided by 9, produces a result of 20, confirming that 68 degrees F equals 20 degrees C.
Key Reference Temperatures
A few reference points are helpful for quickly estimating or checking conversions. The freezing point of water is 32 degrees F, which equals 0 degrees C. Water boils at 212 degrees F, corresponding to 100 degrees C at standard atmospheric pressure.
Normal human body temperature is generally accepted as 98.6 degrees F, which converts to 37 degrees C. A unique point where the two scales numerically align is at -40 degrees, meaning -40 degrees F is the same temperature as -40 degrees C.