Network Address Calculator
Find the network address (subnet ID) for any IP address and CIDR prefix length.
- Free to use
- Accurate results
- No registration required
- Works on all devices
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.