Subnet / CIDR Calculator

Enter an IP address and CIDR prefix to get the network and broadcast address, subnet mask and usable host range.

IP Address

Prefix Length (CIDR): /24

CIDR Notation

192.168.1.0/24

Network Address

192.168.1.0

Broadcast Address

192.168.1.255

Subnet Mask

255.255.255.0

Wildcard Mask

0.0.0.255

First Usable IP

192.168.1.1

Last Usable IP

192.168.1.254

Total Addresses

256

Usable Hosts

254

IP Class

IPv4 only. /31 and /32 subnets have no usable host range (point-to-point links and single-host routes use every address, per RFC 3021).

How to use Subnet / CIDR Calculator

Enter an IP address, e.g. 192.168.1.0.
Set the CIDR prefix length with the slider.
Read off the network address, broadcast address, subnet mask and usable host range.

→ look up DNS records for a domain

Frequently asked questions

What does the prefix length (the /24 part) actually mean?

It's the number of leading bits in the 32-bit IP address reserved for the network portion — the remaining bits identify hosts within that network. A /24 reserves 24 bits for the network, leaving 8 bits (256 addresses) for hosts.

Why do /31 and /32 show 0 usable hosts?

A /32 is a single address with no room for a separate network/broadcast address, and a /31 (RFC 3021) is specifically designed for point-to-point links where both addresses in the pair are used directly, without a broadcast address in between.

Does this support IPv6?

No — this calculator is IPv4 only.

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