Subnet and CIDR Calculator
Enter a network in CIDR notation to see its range, mask, and how many addresses it holds. Works for IPv4 and IPv6.
Details for 192.168.1.0/24
- 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
- Total addresses
- 256
- Range type
- Private network (RFC 1918)
How to read CIDR notation
CIDR notation describes a block of addresses with two parts: a starting address and a number after a slash. In 192.168.1.0/24, the /24 is the prefix length. It says the first 24 bits are fixed and identify the network. The bits that remain are free to number individual devices.
A bigger prefix number means a smaller block, because fewer bits are left over. Each step halves the size: a /25 is half of a /24.
Common IPv4 sizes
| Prefix | Netmask | Addresses | Usable hosts | Typical use |
|---|---|---|---|---|
/8 | 255.0.0.0 | 16,777,216 | 16,777,214 | Very large private networks |
/16 | 255.255.0.0 | 65,536 | 65,534 | A campus or large site |
/24 | 255.255.255.0 | 256 | 254 | A home or small office |
/27 | 255.255.255.224 | 32 | 30 | A small department or VLAN |
/30 | 255.255.255.252 | 4 | 2 | A link between two routers |
/32 | 255.255.255.255 | 1 | 1 | A single host |
What the results mean
- Network is the first address in the block. It names the block itself.
- Netmask is the prefix written the older way, as four numbers. Wildcard mask is its inverse, used in some router and firewall rules.
- Broadcast is the last address. Traffic sent to it reaches every device on the network.
- Usable hosts is the total minus the network and broadcast addresses, which cannot be given to a device.
Two IPv4 sizes are special. A /31 has only two addresses and uses both, for links between two routers. A /32 is a single address.
IPv6 is different
IPv6 has no broadcast address, so every address in a block can be used. The standard size for one network is a /64, which holds about 18 quintillion addresses. Providers typically delegate a larger block to a home or business, such as a /56 or /48, which the router divides into /64 networks. The calculator shows how many fit.
Planning a network
Use the split option to divide a block into equal parts, for example one /24 into four /26 networks for separate departments or VLANs. The "Range type" line tells you whether a block is private, public, or reserved. For what those ranges are for, see public vs private IP addresses. To check whether your provider uses the shared range 100.64.0.0/10, read what is CGNAT.