def celsius_to_farenheit(t):
    t_fahrenheit = t*(9/5)+32
    return t_fahrenheit

answer = 30
t_celsuis = float(answer)
t = celsius_to_farenheit(t_celsuis)
print("Farenheit:", t)
Farenheit: 86.0
def show_user_menu(): # Menu function
    print('\nMenu Options:') # Using \n for new line separator
    print('\n1. Fahrenheit to Celsius')
    print('2. Celsius to Fahrenheit')
    print('3. Fahrenheit to Kelvin')
    print('4. Kelvin to Fahrenheit')
    print('5. Celsius to Kelvin')
    print('6. Kelvin to Celsius')
    print('\nType "q" to End Program')    
    
def f_to_c(): # Fahrenheit to Celsius function
    answer = input('Enter a temperature in Fahrenheit: ')
    t_fahrenheit = float(answer)
    t = float((t_fahrenheit - 32) * 5/9)
    print("\nCelsius: ",t)
       
def c_to_f(): # Celsius to Fahrenheit function
    answer = input('Enter a temperature in Celsius: ')
    t_celsius = float(answer)
    t = float((t_celsius * 9/5) + 32)
    print("\nFahrenheit: ",t)
    
def f_to_k(): # Fahrenheit to Kelvin function
    answer = input('Enter a temperature in Fahrenheit: ')
    t_fahrenheit = float(answer)
    t = float(t_fahrenheit-32) * 5/9 + 273.15
    print("\nKelvin: ",t)
    
def k_to_f(): # Kelvin to Fahrenheit function
    answer = input('Enter a temperature in Kelvin: ')
    t_kelvin = float(answer)
    t = (t_kelvin - 273.15) * 9/5 + 32
    print("\nFahrenheit: ",t)
    
def c_to_k(): # Celsius to Kelvin function
    answer = input('Enter a temperature in Celsius: ')
    t_celsius = float(answer)
    t = t_celsius + 273.15
    print("\nKelvin: ",t)
    
def k_to_c(): # Kelvin to Celsius function
    answer = input('Enter a temperature in Kelvin: ')
    t_kelvin = float(answer)
    t = t_kelvin - 273.15
    print("\nCelsius: ", t) 
    
def undefined(): # Invalid option function
    print("\nThat is not a valid option...")
    print ("\nPlease try again!")


loop = True # Loop program after invalid option or conversion functions

while loop:
    show_user_menu()
    option = input('Select an option from the menu above: ')
    
    if option not in ('1', '2', '3', '4', '5', '6', 'q'):
        undefined()       

    if option == '1':
        f_to_c() 
        
    if option == '2':
        c_to_f() 
               
    if option == '3':
        f_to_k() 
        
    if option == '4':
        k_to_f() 
      
    if option == '5':
        c_to_k() 
       
    if option == '6':
        k_to_c() 
           
    if option == 'q': # End program loop if q is selected
        print ("\nProgram Ended")
        loop = False

Menu Options:

1. Fahrenheit to Celsius
2. Celsius to Fahrenheit
3. Fahrenheit to Kelvin
4. Kelvin to Fahrenheit
5. Celsius to Kelvin
6. Kelvin to Celsius

Type "q" to End Program

That is not a valid option...

Please try again!

Menu Options:

1. Fahrenheit to Celsius
2. Celsius to Fahrenheit
3. Fahrenheit to Kelvin
4. Kelvin to Fahrenheit
5. Celsius to Kelvin
6. Kelvin to Celsius

Type "q" to End Program

Celsius:  10.0

Menu Options:

1. Fahrenheit to Celsius
2. Celsius to Fahrenheit
3. Fahrenheit to Kelvin
4. Kelvin to Fahrenheit
5. Celsius to Kelvin
6. Kelvin to Celsius

Type "q" to End Program

Kelvin:  260.92777777777775

Menu Options:

1. Fahrenheit to Celsius
2. Celsius to Fahrenheit
3. Fahrenheit to Kelvin
4. Kelvin to Fahrenheit
5. Celsius to Kelvin
6. Kelvin to Celsius

Type "q" to End Program

Program Ended
def ask_for_conversion():
    conversion_type = input("What conversion do you want to do? 1. Celsius --> Farenheit or 2. Farenheit --> Celsius")
    if conversion_type=="1":
        def fahrenheit_to_celsius(t):
            t_celsius = (t-32)*(5/9)
            return t_celsius
        answer = input('Enter a temperature in Fahrenheit: ')
        t_fahrenheit = float(answer)
        t = fahrenheit_to_celsius(t_fahrenheit)
        print("Celsius: ", t)
    elif conversion_type=="2":
        answer = input('Enter a temperature in Celsius: ')
        t_celsuis = float(answer)
        t = celsius_to_farenheit(t_celsuis)
        print("Farenheit:", t)
    else:
        print("Select a valid conversion type, 1 or 2")

ask_for_conversion()
Farenheit: 50.0
quit = False
while quit == False:
    ask_for_conversion()
    another_conversion = input("Press 'q' to quit, or any other key to do another conversion")
    if another_conversion=="q":
        break
    else:
        "Let's do another conversion!"
Celsius:  10.0
Celsius:  10.0
Celsius:  37.77777777777778
def fahrenheit_to_celsius(t):
    t_celsius = (t-32)*(5/9)
    return t_celsius

def celsius_to_farenheit(t):
    t_fahrenheit = t*(9/5)+32
    return t_fahrenheit
# T(°C) = T(K) - 273.15
def celsius_to_kelvin(t):
    t_celsuis=t-273.15
    return t_celsuis

def kelvin_to_celsius(t):
    t_kelvin=t+273.15
    return t_kelvin

# Converting Farenheit --> Celsius --> Kelvin
def farenheit_to_kelvin(t):
    t_celsuis=fahrenheit_to_celsius(t)
    t_kelvin=t_celsuis-273.15
    return t_kelvin

# Converting Kelvin --> Celsius --> Farenheit
def kelvin_to_farenheit(t):
    t_celsuis=t+273.15
    t_fahrenheit = celsius_to_farenheit(t_celsuis)
    return t_fahrenheit


while True:
    conversion_type=input("What you do want to convert: 1. Celsius to Kelvin, 2. Kelvin to Celsius, 3. Farenheit to Kelvin or 4. Kelvin to Farenheit")
    if conversion_type=="1":
        answer = input('Enter a temperature in Celsius: ')
        t_fahrenheit = float(answer)
        t = celsius_to_kelvin(t_fahrenheit)
        print("Kelvin: ", t)
    elif conversion_type=="2":
        answer = input('Enter a temperature in Kelvin: ')
        t_fahrenheit = float(answer)
        t = kelvin_to_celsius(t_fahrenheit)
        print("Celsius: ", t)
    elif conversion_type=="3":
        answer = input('Enter a temperature in Farenheit: ')
        t_fahrenheit = float(answer)
        t = farenheit_to_kelvin(t_fahrenheit)
        print("Celsius: ", t)
    elif conversion_type=="4":
        answer = input('Enter a temperature in Kelvin: ')
        t_fahrenheit = float(answer)
        t = kelvin_to_farenheit(t_fahrenheit)
        print("Farenheit: ", t)
    else:
        print("Enter a valid number: 1, 2, 3 or 4")
    another_conversion = input("Press 'q' to quit, or any other key to do another conversion")
    if another_conversion=="q":
        break
    
Kelvin:  -263.15