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🌐 IPv4 Subnet Calculator
Calculate network address, broadcast, host range and host count from an IP and CIDR prefix.
About this IPv4 Subnet Calculator
Subnetting divides an IP network into smaller ranges, and the CIDR prefix controls how big each range is. Give this calculator any IPv4 address and prefix and it works out the netmask, network and broadcast addresses, the first and last usable hosts, and the host counts — the numbers you need when configuring routers, servers, cloud VPCs and firewalls.
How to use it
- Type an IPv4 address, for example 192.168.1.10.
- Enter the CIDR prefix, for example 24.
- Click Calculate subnet.
- Read the full breakdown in the table.
Example
192.168.1.10 with /24 gives network 192.168.1.0, broadcast 192.168.1.255, usable hosts 192.168.1.1 to 192.168.1.254 — 254 hosts in total.
Frequently asked questions
Why are 2 addresses subtracted for usable hosts?
In a normal subnet the network address names the network itself and the broadcast address reaches every host, so neither can be assigned to a device.
What about /31 and /32?
A /32 is a single host route (1 address), and /31 links are a special point-to-point case — the table reports their raw ranges.
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