I am a little bit confused about how to calculate the memory capacity I am a little bit confused about how to calculate the memory capacity.

word=data lines size
byte=8 bit
n=adresse lines size



  Most of the people use this formula to calculate the capacity of the
  memory: C=(2^n*word)/8 octet


Is this formula correct when speaking about byte-addressable? Because if we have byte-addressable memory, I think the capacity will be 2^n octet.

If this is correct why people use the formula in all cases? If not can you please explain why to me?

Thanks you.
This formula assumes that memory is word-addressable rather than byte-addressable. The number of words that can be addressed is $2^n$. If you want to convert this from words to bytes, you can use the formula (in which word stands for the word size in bits). If you want to convert it to kilobytes, for example, you need to multiply by the word size in bits, and divide by $8192$. And so on. Come up with your own formulas!