Thought I'd give /u/Enjgine'd code a refactoring - https://redd.it/avnpue

first.py

import os


def cls():
    os.system('cls' if os.name == 'nt' else clear)


# moved the first conversion into its own function for easier testing (either manual or automated)
def dist2cm(mode, distance):
    # concert all to cm
    if mode == m:
        distance *= 100
    elif mode == inch:
        distance *= 2.54
    elif mode == foot:
        distance *= 30.48
    else:
        distance *= 1
    return distance


def printtarget(target, distance):
    # convert to desired output
    if target == cm:
        print(distance, 'cm')
    elif target == m:
        distance = float(distance) / 100
        print(distance, 'm')
    elif target == inch:
        distance = float(distance) / 2.54
        print(distance, 'inch')
    elif target == foot:
        distance = float(distance) / 30.48
        print(distance, 'foot')


cm = "cm"
m = "m"
inch = "inch"
foot = "foot"

while True:
    mode = input('Enter starting unit (cm,m,inch,foot): ')
    # moved float() to adhere to DRY - Don't Repeat Yourself :)
    distance = float(input('Enter the length you wish to convert: '))
    target = input('Enter your target unit (cm,m,inch,foot): ')

    distance = dist2cm(mode, distance)
    printtarget(target, distance)

    # no need for the wait variable, as it's not in use
    input("Press enter to continue.")
    cls()
    pass