Subnet Calculator
Calculate subnet masks and network information
IP Address & CIDR
Enter IP address and CIDR notation
Calculate subnet details for any IP address and subnet mask combination. Get the network address, broadcast address, usable host range, number of hosts, and CIDR notation. Split networks into subnets or find the optimal subnet mask for a required number of hosts.
Key Features
- ✓Subnet mask to CIDR conversion
- ✓Network and broadcast address calculation
- ✓Usable host range and count
- ✓Subnet splitting (divide a network into smaller subnets)
- ✓Find optimal mask for N hosts
- ✓Visual subnet map
How to Subnet Calculator
- 1
Enter IP and subnet mask
Type an IP address and subnet mask (e.g., 192.168.1.0 / 255.255.255.0).
- 2
View subnet details
See network range, usable hosts, broadcast address, and CIDR.
- 3
Split or aggregate
Optionally divide the network into smaller subnets.
Common Use Cases
- •Designing network addressing for new office locations
- •Splitting a /24 into smaller /28 or /30 subnets
- •Determining the right subnet mask for a given number of hosts
- •CCNA and networking certification study
Frequently Asked Questions
What is a subnet mask?▼
A subnet mask defines which portion of an IP address identifies the network and which identifies the host. For example, 255.255.255.0 (/24) means the first three octets are the network, and the last octet identifies individual hosts.
Why are 2 addresses always unusable?▼
The first address in a subnet is the network address and the last is the broadcast address. Neither can be assigned to a host, so a /24 with 256 total IPs has only 254 usable.