Subnet Calculator

Work out the network address, subnet mask, broadcast address and usable host range of any IPv4 or IPv6 network. Results update as you type.

IP address or CIDR block

Common IPv4 subnet sizes

CIDR	Subnet mask	Wildcard	Total addresses	Usable hosts
/16	255.255.0.0	0.0.255.255	65,536	65,534
/22	255.255.252.0	0.0.3.255	1,024	1,022
/24	255.255.255.0	0.0.0.255	256	254
/25	255.255.255.128	0.0.0.127	128	126
/26	255.255.255.192	0.0.0.63	64	62
/27	255.255.255.224	0.0.0.31	32	30
/28	255.255.255.240	0.0.0.15	16	14
/29	255.255.255.248	0.0.0.7	8	6
/30	255.255.255.252	0.0.0.3	4	2
/31	255.255.255.254	0.0.0.1	2	2
/32	255.255.255.255	0.0.0.0	1	1

An IPv4 network reserves its first address as the network identifier and its last as the broadcast address, so a /24 holds 256 addresses but only 254 usable hosts.
/31 is the exception: RFC 3021 allows both of its addresses to be used on point-to-point links. A /32 is a single host route.
IPv6 has no broadcast address and does not reserve the first or last address of a prefix, so every address in the block is usable.
If the address you enter is not the network address, it is masked down to one. Entering 10.1.2.200/24 gives you the 10.1.2.0/24 block.

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