Subnet Hosts Calculator

Calculate the number of usable IPv4 host addresses for a given subnet prefix length.

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Examples

FAQ

What is a CIDR prefix?

It's the number of bits set to 1 in the subnet mask.

Why subtract 2 hosts?

Network and broadcast addresses are not usable.

Can prefixes be 31 or 32?

Yes, but they allow at most 0 or 1 usable host.

Does this work for IPv6?

No, this formula is specific to IPv4.

Additional Information

No additional information available.

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