subnet calculation determines the network address, broadcast address, usable IP range, and number of hosts for a given IP address and subnet mask. You can do it manually or use our Subnet Calculator for instant results.
Manual Subnet Calculation Steps
Given: IP 192.168.1.45, Mask 255.255.255.0 (/24)
- Find the network address: Bitwise AND between IP and mask. For /24: take the first three octets unchanged, set last octet to 0. Result: 192.168.1.0
- Find the broadcast address: Set all host bits to 1. For /24: set last octet to 255. Result: 192.168.1.255
- Usable host range: Network address + 1 to Broadcast - 1. Result: 192.168.1.1 to 192.168.1.254
- Number of hosts: 2^(host bits) - 2. For /24: 2^8 - 2 = 254 hosts
Subnetting Example with /25
| Field | Value |
|---|---|
| IP / CIDR | 192.168.1.45 /25 |
| Subnet mask | 255.255.255.128 |
| Network address | 192.168.1.0 |
| Broadcast | 192.168.1.127 |
| Usable range | 192.168.1.1 - 192.168.1.126 |
| Usable hosts | 126 |
What Is 192.168.1.1/24 Subnet?
192.168.1.1/24 means the host IP is 192.168.1.1 in the 192.168.1.0/24 network. The router is typically assigned .1 in this case. All devices from 192.168.1.1 to 192.168.1.254 are on the same local network.
Common questions about How to Calculate a Subnet
What does 255.255.255 mean?
If you see 255.255.255.0 as a subnet mask, it means you are on a /24 network with room for 254 hosts. All three 255 octets are the network portion; the final 0 is the host portion.
Related: Subnets | CIDR | Subnet Calculator