Subnet Calculator
Calculate IPv4 subnets from CIDR or netmask: network, broadcast, host range, usable hosts and wildcard mask. Free online IP subnet calculator with subnetting.
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Part of the toolkit
How to use Subnet Calculator
- 1Type an IPv4 address with a CIDR prefix (192.168.1.10/24) or a subnet mask (192.168.1.10 255.255.255.0), or pick the prefix from the dropdown
- 2Press Calculate to get the network and broadcast address, first and last usable host, number of hosts, wildcard mask, class and binary view
- 3Optionally split the network into smaller subnets to get a full subnetting table
Frequently asked questions
How many usable hosts are in a subnet?▾
Usable hosts = 2^(32 − prefix) − 2, because the network and broadcast addresses are reserved. A /24 has 254 usable hosts, a /26 has 62, a /30 has 2. A /31 point-to-point link uses both addresses (RFC 3021) and a /32 is a single host.
What is CIDR notation?▾
CIDR writes the subnet mask as the number of leading 1 bits after a slash. 192.168.1.0/24 means the mask 255.255.255.0 — the first 24 bits are the network and the last 8 bits are hosts.
What is a wildcard mask?▾
A wildcard mask is the inverse of the subnet mask (255.255.255.255 minus the mask). It is used in Cisco ACLs and OSPF; the wildcard for 255.255.255.0 is 0.0.0.255.
Which IP ranges are private?▾
RFC 1918 private ranges are 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. 100.64.0.0/10 is carrier-grade NAT, 127.0.0.0/8 is loopback and 169.254.0.0/16 is link-local.
How do I find the network address?▾
Apply a bitwise AND between the IP and the subnet mask. For 192.168.1.130/26 the mask is 255.255.255.192, so the network is 192.168.1.128 and the broadcast is 192.168.1.191.
Embed Subnet Calculator on your website▾
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