C# Program to Convert Fahrenheit to Celsius

Temperature conversion between Fahrenheit and Celsius is a common programming task. In C#, you can easily convert Fahrenheit to Celsius using a simple mathematical formula and display the results with proper formatting.

The conversion formula subtracts 32 from the Fahrenheit temperature, then multiplies by 5/9 to get the equivalent Celsius temperature.

Formula

The mathematical formula for converting Fahrenheit to Celsius is −

celsius = (fahrenheit - 32) * 5 / 9

Using Direct Conversion

Here's a simple program that converts a fixed Fahrenheit temperature to Celsius −

using System;

class TemperatureConverter {
   static void Main(string[] args) {
      double fahrenheit = 97;
      double celsius;
      
      Console.WriteLine("Fahrenheit: " + fahrenheit);
      celsius = (fahrenheit - 32) * 5 / 9;
      Console.WriteLine("Celsius: " + celsius.ToString("F2"));
   }
}

The output of the above code is −

Fahrenheit: 97
Celsius: 36.11

Using a Method for Conversion

For better code organization, you can create a dedicated method to handle the conversion −

using System;

class TemperatureConverter {
   static double FahrenheitToCelsius(double fahrenheit) {
      return (fahrenheit - 32) * 5 / 9;
   }
   
   static void Main(string[] args) {
      double[] temperatures = { 32, 68, 98.6, 100, 212 };
      
      Console.WriteLine("Fahrenheit\tCelsius");
      Console.WriteLine("------------------------");
      
      foreach (double temp in temperatures) {
         double celsius = FahrenheitToCelsius(temp);
         Console.WriteLine($"{temp}°F\t\t{celsius:F1}°C");
      }
   }
}

The output of the above code is −

Fahrenheit	Celsius
------------------------
32°F		0.0°C
68°F		20.0°C
98.6°F		37.0°C
100°F		37.8°C
212°F		100.0°C

Interactive Temperature Converter

This example demonstrates conversion with multiple temperature values and formatted output −

using System;

class Program {
   static void Main() {
      string[] descriptions = { "Freezing point", "Room temperature", "Body temperature", "Boiling point" };
      double[] fahrenheitValues = { 32, 68, 98.6, 212 };
      
      Console.WriteLine("Temperature Conversion Table");
      Console.WriteLine("============================");
      
      for (int i = 0; i < fahrenheitValues.Length; i++) {
         double fahrenheit = fahrenheitValues[i];
         double celsius = (fahrenheit - 32) * 5 / 9;
         
         Console.WriteLine($"{descriptions[i]}: {fahrenheit}°F = {celsius:F1}°C");
      }
   }
}

The output of the above code is −

Temperature Conversion Table
============================
Freezing point: 32°F = 0.0°C
Room temperature: 68°F = 20.0°C
Body temperature: 98.6°F = 37.0°C
Boiling point: 212°F = 100.0°C

Key Points

• The conversion formula is (fahrenheit - 32) * 5 / 9

• Use ToString("F2") or string interpolation with :F2 to format decimal places

• Creating a separate method makes the code reusable and more organized

• Always ensure proper data types − use double for precise decimal calculations

Conclusion

Converting Fahrenheit to Celsius in C# is straightforward using the formula (fahrenheit - 32) * 5 / 9. You can implement this as a direct calculation or wrap it in a method for reusability, and use string formatting to control the display precision of the results.