Convert Fahrenheit to Celsius Part I

Temperature Conversion: Learn

The metric system uses the Celsius scale to measure temperature. However, temperatures are still measured on the Fahrenheit scale in the U.S.

Water freezes at 0° Celsius and boils at 100° Celsius, which is a difference of 100°. Water freezes at 32° Fahrenheit and boils at 212° Fahrenheit, which is a difference of 180°. Therefore each degree on the Fahrenheit scale is equal to 100/180 or 5/9 degrees on the Celsius scale.

How to convert Fahrenheit temperatures to Celsius:

  • Subtract 32° to adjust for the offset in the Fahrenheit scale.
  • Multiply the result by 5/9.

Example: Convert 98.6°F to Celsius

  • 98.6 - 32 = 66.6
  • 37 * 9/5 = 333/5 = 66.6
  • 66.6 + 32 = 98.6°F

There is a mental math method to approximate the Fahrenheit to Celsius conversion. The ratio of 5/9 is approximately equal to 0.55555....

How to approximately convert Fahrenheit temperatures to Celsius with mental math:

  • Subtract 32° to adjust for the offset in the Fahrenheit scale.
  • Divide the difference by 2 (multiply by 0.5)
  • Take one-tenth of that quotient (0.5 * 1/10 = 0.05) and add it to the quotient

Example: Convert 98.6°F to Celsius

  • 98.6 - 32 = 66.6
  • 66.6 / 2 = 33.3
  • 33.3 * 1/10 is approximately 3.3, so 36.6+3.3 = 39.6°C

Converting Temperature: Practice

Convert and round to the nearest degree.

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°F = °C

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