# how to find how many usable subnets?



## graveleather (Oct 6, 2007)

i know how if u borrow lets say 3 bits u can make 8 subnets but how many usable subnets?


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## lorjack (Nov 15, 2007)

Do you mean usable hosts? If you have a /27 then you get 8 subnets. But you'll get 30 usable host addresses per subnet.


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## PinoyIT (Feb 28, 2011)

2 ^ # of bits borrowed = # of subnets
(2 ^ # of remaining host bits) - 2 = # of usable hosts


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