Subnet Calculator
Enter an IPv4 address and a CIDR prefix to instantly get the network address, usable host range, broadcast address, subnet mask, and total host count.
What Is a Subnet?
A subnet (subnetwork) splits a larger IP network into smaller, logically separated segments. Subnetting improves performance by containing broadcast traffic, and improves security by isolating groups of hosts.
The CIDR prefix (for example /24) states how many bits define the network portion of the address. A /24 reserves 24 bits for the network and leaves 8 bits for hosts, giving 254 usable addresses.
Common CIDR Blocks
255.255.255.252
2 usable — point-to-point links
255.255.255.248
6 usable — small device groups
255.255.255.240
14 usable — rack management VLANs
255.255.255.0
254 usable — standard LAN segment
255.255.254.0
510 usable — larger access networks
255.255.0.0
65,534 usable — large enterprise scope
Why Subnetting Matters for Infrastructure Operations
Clean subnet design keeps management traffic separated from production traffic. Out-of-band management networks — where BMC, iDRAC, iLO, and iBMC interfaces live — are typically placed on dedicated subnets so hardware stays reachable even when the production network is down.
Segment management networks
Keep out-of-band interfaces isolated from production.
Plan address capacity
Size subnets to rack, row, and pod density.
Contain broadcast domains
Reduce noise and blast radius during incidents.
Subnetting Questions, Answered
What is CIDR notation?
CIDR notation writes an IP address followed by a slash and the number of network bits, like 192.168.1.0/24. The /24 means the first 24 bits identify the network, leaving 8 bits for hosts — equivalent to the subnet mask 255.255.255.0.
What is a CIDR block?
A CIDR block is the range of IP addresses covered by a CIDR prefix. For example, 10.0.0.0/16 is a block of 65,536 addresses from 10.0.0.0 to 10.0.255.255.
What is subnetting?
Subnetting is dividing a larger IP network into smaller segments (subnets). It contains broadcast traffic, improves security through isolation, and lets address space be allocated to match real capacity needs.
How do you subnet a network?
Decide how many hosts each segment needs, choose a prefix length that provides them (e.g., /26 for up to 62 hosts), and carve the parent network into consecutive blocks of that size. This calculator gives the network, broadcast, and usable range for any block instantly.
See every device on every subnet — including the hardware layer
Sensaka discovers and monitors servers, storage, and network devices across your management networks, connecting IP, asset, and business context in one view.