1. Celsius and Fahrenheit
Unit 25
Celsius and Fahrenheit

2. Basic Principles of Celsius and Fahrenheit Conversions
The temperature measurement used most commonly in the United States is the Fahrenheit (F) scale.
In the metric system used by most other countries, Celsius (C) or Centigrade is used.
In the Fahrenheit system, the freezing point is 32°, and the boiling point is 212°.
In the Celsius system, the freezing point is 0°, and the boiling point is 100°.

3. Converting Fahrenheit and Celsius
To convert Fahrenheit temperatures to Celsius temperatures, the following formula is used:
C = (F - 32) × 5/9 or C = (F - 32) x
To convert Celsius temperatures to Fahrenheit temperatures, the following formula is used:
F = 9/5C + 32 or F = 1.8C + 32

4. Celsius and Fahrenheit
Example: Convert 60°C to degrees Fahrenheit.
Use the formula: F = 1.8C + 32
F = (1.8 x 60) + 32
F =
F = 140°
60°C = 140°F

5. Practical Problem
A physical therapist (PT) is filling a whirlpool bath after it has been disinfected. The temperature of the bath should be set at 100°F. The digital control on the whirlpool bath is calculated for degrees Celsius.
What °C temperature should she use?

6. Practical Problem
Use the formula to convert Fahrenheit to Celsius: C = (F - 32) x
C = (100 – 32) x
C = 68 x =
The whirlpool bath should be set at 37.8°C.