Shows which bits belong to the network portion of the IPv4 address.
CIDR tool
IPv4 subnet calculator
Turn an IPv4 address and CIDR prefix into the network details you actually need.
Enter an IPv4 address with a CIDR prefix, for example 192.168.1.10/24.
Quick guide
CIDR and subnetting in plain English
CIDR notation combines an IP address with a prefix length. A /24, for example, means the first 24 bits identify the network and the remaining bits identify addresses inside that network.
The calculator runs in your browser. The address you enter is not sent to a remote subnet API.
The inverse of the subnet mask, often used in network and access-control configuration.
For ordinary subnets, this excludes the network and broadcast addresses. /31 and /32 are handled separately.
The IPv4 address and CIDR prefix are converted into a network mask, network address, broadcast address and usable host range using binary subnet boundaries.
- Planning a local network
- Checking whether two addresses share a subnet
- Understanding CIDR blocks and host capacity
Terminal shortcut
Prefer the command line?
Calculate an IPv4 subnet from a short command.
> subnet 192.168.1.10/24
Run in Terminal ->