IPv4 Subnet Calculator
Calculate subnet mask, network address, broadcast, and host range.
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What it does
Enter an IPv4 address and a CIDR prefix to get the network address, subnet mask, broadcast address, first and last usable host and the total number of hosts. Any address inside the block works, so you can paste a host IP and see which subnet it belongs to.
Prefix lengths from /0 to /32 are supported. For /31 point-to-point links (RFC 3021) and /32 single hosts, no addresses are reserved for network and broadcast, and the host count reflects that. Results update as you type.
When you would reach for it
- Plan subnets for a VPC or VLAN and confirm each block's usable host range.
- Find the network and broadcast address for a server IP while writing firewall rules.
- Check how many hosts a /22 or /27 gives before requesting address space.
- Verify that two IPs fall in the same subnet when debugging routing.
Also found by searching
- ipv4
- subnet
- cidr
- netmask
- network
- broadcast