Free Subnet Calculator – IPv4 Network Address Calculator Online
Subnetting is a fundamental networking concept that allows you to divide a larger network into smaller, more manageable sub-networks. Understanding subnets is essential for network engineers, system administrators, and anyone working with IP addressing. Our free subnet calculator makes it easy to compute all the key details of any IPv4 subnet in seconds, without needing to perform manual binary calculations.
With this tool you can enter any valid IPv4 address along with a subnet mask in CIDR notation (such as /24) or dotted decimal format (such as 255.255.255.0). The calculator instantly determines the network address, broadcast address, first and last usable host addresses, total number of usable hosts, wildcard mask, IP class, and the full binary representation of the subnet mask.
Quick-select buttons for the most commonly used CIDR prefixes — /8, /16, /24, /28, and /30 — let you rapidly switch between subnet sizes. This is particularly useful when planning network architectures or troubleshooting connectivity issues. Each prefix is annotated with its approximate host capacity so you can choose the right size at a glance.
Whether you are studying for a networking certification like CCNA, designing a corporate LAN, or simply trying to understand how IP addressing works, this subnet calculator provides all the information you need in a clean, easy-to-read format. All calculations happen locally in your browser — no data is sent to any server.