Subnet calculator
Enter an IPv4 or IPv6 network in CIDR notation, or an IPv4 address followed by a netmask. Everything is calculated in your browser; nothing is sent to us.
Result
- Address
- Network (CIDR)
- Network address
- Broadcast address
- First usable host
- Last usable host
- Usable hosts
- Total addresses
- Netmask
- Wildcard mask
- Address type
- Binary (network bits highlighted)
- Address
- Expanded address
- Network (CIDR)
- First address
- Last address
- Total addresses
- Number of /64 subnets
- Address type
What this tool does
The subnet calculator works out everything about an IP network from its CIDR notation, such as 192.168.1.0/24, or from an address followed by a netmask, such as 10.0.0.1 255.255.255.0.
For IPv4 it shows the network and broadcast addresses, the first and last usable host, how many hosts fit, the netmask, the wildcard mask, and a binary view with the network bits highlighted. For IPv6 it shows the range of the prefix, its size and how many /64 networks it contains.
Everything is calculated in your browser; nothing you type is sent to iplover.
How to read the results
- Network address is the first address of the block and stands for the network itself. Broadcast address is the last one and reaches every host at once. Neither can be given to a device, which is why usable hosts is the total minus two.
- First and last usable host give the range you can assign to devices, for example when you set up a DHCP pool on a router.
- In the binary view, the highlighted bits are the same for every address in the network and the rest vary from host to host. The point where the highlight ends is the prefix length.
- Address type tells you whether the range is public or reserved for a special use, such as private networks (RFC 1918) or carrier-grade NAT.
Examples
192.168.1.0/24A typical home or office network: 254 usable hosts.10.0.0.0/8The largest private range: over 16 million addresses.172.16.0.0/12The middle private range, common in cloud networks and Docker.192.168.10.64/26A quarter of a /24: 62 usable hosts.10.0.0.0/30A small point-to-point link: 2 usable hosts.203.0.113.77 255.255.255.248An address with a dotted netmask instead of a prefix length.2001:db8:abcd::/48A typical IPv6 site allocation: 65,536 /64 subnets.
Frequently asked questions
What does CIDR notation like /24 mean?
The number after the slash is how many bits, counted from the left, belong to the network. The remaining bits identify hosts inside it. A /24 leaves 8 bits for hosts, so it holds 28 = 256 addresses.
How many usable hosts are in a /24?
254. A /24 has 256 addresses, but the first is the network address and the last is the broadcast address, so neither can be given to a device.
Why does a /31 have two usable hosts?
A /31 has only two addresses. On point-to-point links between two routers there is no need for a network or broadcast address, so RFC 3021 lets both be used. A /32 is a single address.
What is a wildcard mask?
The netmask with every bit flipped: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use wildcard masks to say which bits must match.
How big is an IPv6 /64?
264 addresses, about 18 quintillion. A /64 is the standard size for a single IPv6 network, because automatic address configuration (SLAAC) needs 64 bits for the host part. Sites usually get a /48 or /56, which they split into /64s.