What is the approximate bandwidth of a 13-WPM International Morse Code transmission?

The bandwidth of an International Morse Code (CW) transmission is directly proportional to the speed at which it is sent. A standard, widely accepted rule of thumb in amateur radio is to estimate CW bandwidth by multiplying the transmission speed in Words Per Minute (WPM) by a constant factor of 4. Applying this simple formula to the question: 13 WPM multiplied by 4 yields an approximate bandwidth of 52 Hz. This extremely low bandwidth requirement demonstrates why CW is such an efficient mode for crowded band conditions.