About IP Subnet Calculator
An IP subnet calculator saves doing binary in your head when you plan a network, whether you're carving a cloud VPC into subnets, sizing an office LAN, writing a firewall rule for a whole range, or checking whether two addresses sit in the same subnet. Enter an address with a prefix length, like 192.168.1.10/24, or with a dotted mask such as 255.255.255.0. For a firewall rule covering a whole hosting company, the ASN Lookup lists every range it announces.
For IPv4 you get the network and broadcast address, the first and last usable host, the number of hosts, the netmask and wildcard mask, a binary view that shows where the network part ends, the old address class, and whether the range is private or public. IPv6 prefixes such as 2001:db8::/48 work too. To plan smaller networks, split the range by a longer prefix, say a /24 into /26 blocks, and read every subnet from the table. To turn an address into its integer, hex or reverse DNS form, use the IP Address Converter. The calculator runs in your browser, is free and unlimited, and keeps working offline once the page has loaded.
How to use IP Subnet Calculator
- 1Enter an address
Type an IPv4 or IPv6 address in CIDR form, such as 10.0.0.0/16, or an IPv4 address with a dotted mask.
- 2Read the results
See the network, broadcast, usable host range, host count, masks, class and type.
- 3Split into subnets
Choose a longer prefix to divide the range into equal smaller subnets, listed in a table.
Why use Cubfile for this
- CIDR or dotted mask
Both 192.168.1.10/24 and 192.168.1.10 with 255.255.255.0 are understood.
- Wildcard mask
The inverted mask used in Cisco ACLs and OSPF, next to the normal netmask.
- Binary view
See exactly which bits belong to the network and which to the hosts.
- Subnet splitting
Divide a range into smaller subnets, one table row each.