Explosion Tools

Subnet Calculator — IPv4 CIDR

Calculate network address, broadcast, host range, subnet mask, and wildcard mask from any IP and CIDR prefix.. Free, no signup, works in your browser.

/0/8/16/24/32

All calculation happens in your browser. No data is sent to any server.

About Subnet Calculator

This subnet calculator computes all essential IPv4 network parameters from an IP address and CIDR prefix length. Enter any IPv4 address, adjust the CIDR slider from /0 to /32, and instantly see the network address, broadcast address, first and last usable hosts, subnet mask, wildcard mask, total addresses, usable host count, IP class, and binary representations. Useful for network engineers, sysadmins, DevOps, cloud architects, and students studying for CCNA or CompTIA Network+ certifications.

Frequently Asked Questions

What is a subnet calculator?
A subnet calculator takes an IP address and CIDR prefix (like /24) and computes the network boundaries: network address, broadcast address, usable host range, subnet mask, and wildcard mask. It helps you plan IP address allocation in networks.
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation uses a slash followed by a number (e.g., /24) to indicate how many bits of the IP address identify the network. A /24 means the first 24 bits are the network portion, leaving 8 bits (256 addresses) for hosts.
How many usable hosts does a /24 network have?
A /24 network has 256 total addresses but only 254 usable hosts. Two addresses are reserved: the network address (first) and broadcast address (last). For /31 and /32 subnets, all addresses are usable per RFC 3021.

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