Code to measure the length of binary numbers in terms of English nomenclature
Just some points:


This code here:

running = True
counter = 0
while running:
    checker = check(letters(counter))
    if checker == 0:
        pass
    else:
        #Loops through over and over again until a number reaches either 13 or 18
        while checker != 0:
            checker = check(letters(checker))

    #I could have used a "for" loop but it just wasn't working with this :(
    counter += 1
    if counter &gt; maximum:
        running = False


is a bit repetitive and could be easily simplified. First, let's remove the duplicate checker = check(letters(counter)) by using a different loop:

running = True
counter = 0
while running:
    checker = 1 # really any number can be used here
    while checker != 0
        checker = check(letters(counter))
    counter += 1
    if counter &gt; maximum:
        running = False


and then we can change the while loop into a for loop:

running = True
counter = 0
for counter in range(0, maximum + 1):
    checker = 1 # really any number can be used here
    while checker != 0:
        checker = check(letters(counter))

Here:

for ch in binary:
    if ch == '1':
        letter += 3
    if ch == '0':
        letter += 4


Can't you use an else?

for ch in binary:
    if ch == '1':
        letter += 3
    else:
        letter += 4