Network Address Calculator
Find the network address (subnet ID) for any IP address and CIDR prefix length.
- Free to use
- No registration required
- Works on all devices
- Last updated
- 13-09-2026
Enter an IP address and CIDR prefix to find the network address for that subnet.
Your result
203.0.113.4
Network address
Subnet mask255.255.255.252
Broadcast address203.0.113.7
AI explanation
Formula
Network address = IP address AND subnet mask (bitwise AND)Worked example
203.0.113.5 / 30
| Field | Value |
|---|---|
| IP address | 203.0.113.5 |
| CIDR prefix (/n) | 30 |
| Network address | 203.0.113.4 |
| Subnet mask | 255.255.255.252 |
| Broadcast address | 203.0.113.7 |
Assumptions
- IPv4 only.
- The network address identifies the subnet itself and is never assigned to a host (except in /31 point-to-point links, per RFC 3021).
Frequently asked questions
What is a network address used for?
It identifies the subnet as a whole, used in routing tables and configuration to refer to the entire block of addresses rather than any single host.
Can I assign the network address to a device?
No, except for /31 subnets (point-to-point links under RFC 3021) — in all other cases, the network address is reserved and not usable as a host address.
Is the network address the same as the first usable host?
No — the first usable host is one address above the network address (e.g. network .4, first usable .5) in typical subnets.