Subnet calculator
CIDR, masks and address ranges
Examples: 192.168.1.10/24, 10.0.0.1 255.255.0.0 or 2001:db8::1/64. Without a prefix, a single address is calculated.
Binary view
Network bits in red, host bits in grey.
Network
- Address
- 192.168.1.10
- Network
- 192.168.1.0/24
- Netmask
- 255.255.255.0
- Wildcard mask
- 0.0.0.255
- Broadcast
- 192.168.1.255
- First host
- 192.168.1.1
- Last host
- 192.168.1.254
- Usable hosts
- 254
- Number of addresses
- 256
- Class
- C
- Type
- Private (RFC 1918)
Split the network
4 subnets of /26
| # | Network | Usable hosts | Broadcast |
|---|---|---|---|
| 1 | 192.168.1.0/26 | 192.168.1.1 – 192.168.1.62 | 192.168.1.63 |
| 2 | 192.168.1.64/26 | 192.168.1.65 – 192.168.1.126 | 192.168.1.127 |
| 3 | 192.168.1.128/26 | 192.168.1.129 – 192.168.1.190 | 192.168.1.191 |
| 4 | 192.168.1.192/26 | 192.168.1.193 – 192.168.1.254 | 192.168.1.255 |
About this tool
The subnet calculator shows the key facts about a network from an address and a CIDR prefix, or a dotted-decimal mask such as 255.255.0.0. For IPv4 it gives the network address, netmask, wildcard mask, broadcast address, first and last host, number of usable hosts, address class and address type: private RFC 1918, CGNAT, loopback, multicast and so on.
It also handles IPv6: compressed and expanded forms, network prefix, first and last address, total number of addresses and type (link-local, unique local ULA, global unicast and others). A binary view shows the network and host bits of an IPv4 address. When planning an addressing scheme, you can split an IPv4 network into N subnets or by a new prefix, with the host range and broadcast of each one.
How to use it
- Type the address into "Address and prefix", for example 192.168.1.10/24, 10.0.0.1 255.255.0.0 or 2001:db8::1/64.
- Read the values in the "Network" panel and copy the one you need with that row's "Copy" button.
- For IPv4, check the "Binary view" to see where the network bits end and the host bits begin.
- Under "Split the network", choose "Into N subnets" or "By new prefix" and enter the value you want.
Frequently asked questions
Which address formats are accepted?
An IPv4 address with a prefix (/24) or a dotted-decimal mask (255.255.255.0), or an IPv6 address with a prefix from 0 to 128. Without a prefix, the calculation covers a single address. A mask whose 1 bits are not contiguous is rejected.
How are /31 and /32 prefixes handled?
A /31 is treated as a point-to-point link per RFC 3021: both addresses are usable and there is no broadcast address. A /32 is a single host. In every other case, the network and broadcast addresses are excluded from the usable hosts.
How does subnet splitting work?
It is available for IPv4. In "Into N subnets" mode, the requested count is rounded up to the next power of 2; in "By new prefix" mode, the new prefix must be greater than or equal to the current one. The table lists at most the first 256 subnets.
Are the addresses I enter sent to a server?
No. All calculations run in JavaScript in your browser, with no network call. The last address you entered and your split settings are simply remembered in this browser for your next visit.