IP Subnet Calculator (CIDR)

Calculate network, broadcast, host range, mask and wildcard for any IPv4 CIDR — and split it into smaller subnets.

How many usable hosts are in a /24 subnet?

A /24 network has 256 addresses and 254 usable hosts: the first address identifies the network and the last is the broadcast address. In general a /n subnet has 2^(32−n) addresses and 2^(32−n) − 2 usable hosts (a /31 point-to-point link and a /32 single host are exceptions).

CIDR cheat sheet

Prefix	Subnet mask	Addresses	Usable hosts
/8	255.0.0.0	16,777,216	16,777,214
/16	255.255.0.0	65,536	65,534
/24	255.255.255.0	256	254
/26	255.255.255.192	64	62
/28	255.255.255.240	16	14
/30	255.255.255.252	4	2

Enter an address with a prefix (192.168.1.10/24) or with a dotted mask. Fill in Split into to divide the network into equal smaller subnets, for example a /24 into four /26 networks.

Frequently asked questions

What is a wildcard mask?

The inverse of the subnet mask (0.0.0.255 for a /24), used in Cisco ACLs and OSPF.

Which ranges are private?

10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 (RFC 1918).

Does it support IPv6?

Use the IPv6 Address Expander & Compressor for IPv6 prefixes.