The definitions of Channel Capacity and Bandwidth I read are exactly the same, so what's the difference between them/their exact definitions?

The Nyquist formula is C = 2 * B * log2 M, so they can't mean the same thing.

  • They probably are the same, as there is no "official" definition of channel capacity. If you include the context of the term (a full quote or reference), we can say for sure.
    – Ron Trunk
    Commented Mar 10, 2021 at 16:28
  • But the Nyquist formula is C=2Blog2M, so they can't be the same
    – Ariel
    Commented Mar 10, 2021 at 16:29
  • Please include the reference where you see the term "channel capacity,"
    – Ron Trunk
    Commented Mar 10, 2021 at 16:33
  • Ok, I added it.
    – Ariel
    Commented Mar 10, 2021 at 16:37
  • "Channel capacity" is the theoretical maximum of a channel (cable, WDM channel, ...), "bandwidth" is the (currently) usable data rate. imho.
    – Zac67
    Commented Mar 10, 2021 at 16:59

2 Answers 2


There is confusion between the definitions electrical engineers and computer scientists give to bandwidth: for electrical engineers bandwidth is a physical property and limitation of a trasmission channel,and it's measured in Hertz and it's an analog bandwidth. For computer scientists bandwidth is equal to the capacity or maximum data rate of a channel, it's a digital bandwidth and it's measured in bit/s. The two are related by the Nyquist formula, C = 2 * B * log2 M,where B is the analog bandwidth (Hertz) of the physical channel used for digital transmission,M is the number of discrete levels used to digitally represent the signal,C is the capacity or maximum data rate or digital bandwidth (bit/s) of the channel.


Based on my reading of the context, what is referred to as "channel capacity," I would call "Throughput."

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