What is the approximate bandwidth required to transmit a CW signal?

Continuous Wave (CW) or Morse code is the most spectrally efficient mode of transmission used in amateur radio. It relies simply on turning a single radio frequency carrier on and off, which means it requires very little spectrum space. The approximate bandwidth for a standard CW signal is only about 150 Hz. In contrast, an SSB voice signal requires about 2.4 kHz (2400 Hz), and FM voice requires about 10 to 15 kHz. This extremely narrow bandwidth allows many CW signals to fit into a small section of a band and makes CW highly effective for weak-signal communication, since all the transmitter's power is concentrated into a tiny slice of spectrum.