This IP subnet calculator takes an IPv4 address and a CIDR prefix and returns the network address, broadcast address, subnet mask and number of usable hosts.
IP Subnet Calculator
Formula
The subnet mask is derived from the CIDR prefix; the network address is IP AND mask, the broadcast is network OR the inverted mask, and usable hosts = 2^(32 − prefix) − 2.
How to Use This Calculator
- Enter an IPv4 address (e.g. 192.168.1.10).
- Enter the CIDR prefix length (0–32).
- Click Calculate.
Worked Example
192.168.1.10/24 → network 192.168.1.0, broadcast 192.168.1.255, mask 255.255.255.0, 254 usable hosts.
Frequently Asked Questions
What is a CIDR prefix?
CIDR notation (e.g. /24) gives the number of bits used for the network portion of an IP address; the rest are host bits.
How many hosts are in a /24 network?
A /24 network has 256 addresses and 254 usable hosts (excluding the network and broadcast addresses).
How do you find the broadcast address?
Set all host bits to 1: it is the network address OR-ed with the inverted subnet mask.