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Networking

IP Subnet Calculator

Calculate IPv4 network, broadcast, subnet mask and usable host range from CIDR notation.

IPv4 subnet notes

This calculator is for IPv4 CIDR planning. It shows the address range implied by the prefix and treats /31 and /32 networks as special cases where modern point-to-point or host addressing may use addresses differently.

Example

For 192.168.1.25/24, the subnet mask is 255.255.255.0, the network address is 192.168.1.0 and the broadcast address is 192.168.1.255. In a typical LAN, usable host addresses run from 192.168.1.1 through 192.168.1.254.

Common mistakes

A /24 prefix does not mean 24 hosts; it means 24 network bits. Smaller prefixes usually create larger address ranges, while larger prefixes create smaller ranges.

Limitations

It does not check routing policy, VLAN design, DHCP scope reservations, IPv6 ranges or public allocation ownership.

Last reviewed: 2026-05-17

Before relying on this result

Use this calculator together with the formula, assumptions, limitations and examples on the page. If the topic involves health, tax, lending, investment, legal, safety or current-rate decisions, treat the number as an estimate and check the relevant primary source or professional guidance.

Calculator metadata last reviewed: 2026-05-14.