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IP subnet calculator

Enter an IP address with a CIDR prefix or subnet mask and get the network address, broadcast, usable host range, wildcard mask and a binary breakdown — instantly.

🔒 Calculated locally in your browser.

How to calculate a subnet

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1. Enter IP / CIDR

Type something like 192.168.1.130/26 — or pick the mask from the dropdown.

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2. Read the results

Network, broadcast, first and last usable host, host count, wildcard and full binary view.

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3. Copy what you need

Every value has one-click copy — ready for configs and documentation.

Subnetting splits a network into smaller ranges: the prefix length (/26) says how many bits identify the network, and the rest address hosts. A /26 leaves 6 host bits → 64 addresses, 62 usable (network and broadcast are reserved). Common sizes: /24 = 254 hosts (the classic LAN), /30 = 2 hosts (point-to-point links), /32 = a single host route. Check your public address with What Is My IP, or do the binary math by hand with the Number Base Converter.

Subnet calculator FAQ

How many usable hosts are in a /24?

A /24 has 8 host bits → 256 addresses. Two are reserved (network and broadcast), so 254 are usable for devices.

What is CIDR notation?

CIDR (Classless Inter-Domain Routing) writes the subnet mask as a prefix length: 192.168.1.0/24 means the first 24 bits are the network part — the same as netmask 255.255.255.0.

What is a wildcard mask?

The inverse of the subnet mask, used in Cisco ACLs and OSPF configs: for /24 the mask is 255.255.255.0 and the wildcard is 0.0.0.255.

Why are the first and last addresses reserved?

The first address (all host bits 0) names the network itself; the last (all host bits 1) is the broadcast address. Exception: /31 point-to-point links use both addresses (RFC 3021).