Network Subnet Calculator
Proper network subnet planning is essential for efficient IP address management and scalable network infrastructure. Poor subnetting can lead to IP address exhaustion, routing inefficiencies and network segmentation issues that compromise both performance and security.
This tool performs instant subnet calculations from IP addresses and CIDR notation, showing you network addresses, broadcast addresses, usable host ranges, and subnet masks. Whether you’re planning VLANs for an office network, configuring cloud infrastructure, or designing network segmentation for security, accurate subnet calculations are fundamental to network architecture.
100% Private & Secure: All calculations happen locally in your browser. No IP addresses, subnet information, or network details are ever sent to any server or saved anywhere. All subnet analysis happens entirely on your device.
Understanding subnet boundaries, calculating host capacity, and visualizing IP address ranges helps network administrators design efficient networks, prevent addressing conflicts and maintain organised documentation for enterprise environments.
IP Address Input
Quick CIDR Reference
Network Information
Understanding Subnetting
- CIDR notation (e.g., /24) indicates how many bits are used for the network portion of the IP address.
- Subnet masks separate network and host portions. More network bits = fewer hosts per subnet.
- Network address is the first IP in the range (all host bits = 0), used to identify the subnet.
- Broadcast address is the last IP in the range (all host bits = 1), used to send to all hosts.
- Usable hosts exclude network and broadcast addresses. A /24 subnet has 254 usable addresses.
- Wildcard masks are the inverse of subnet masks, commonly used in ACLs and routing protocols.