Subnet Calculator
Our Subnet Calculator helps you determine network information from an IP address and subnet mask. Perfect for network configuration, IP address planning, subnet design, and network troubleshooting.
How to Use This Calculator
Enter an IP address and subnet mask (in dotted decimal format like 255.255.255.0 or CIDR notation), then click "Calculate" to see the network address, broadcast address, usable host IP range, total number of hosts, and usable hosts (excluding network and broadcast addresses). Use this for network configuration, IP address planning, subnet design, network troubleshooting, and CIDR notation conversion. The calculator helps you understand which IP addresses are available for assignment and which are reserved for network and broadcast purposes.
Why Subnet Calculation Matters
Understanding subnet information is essential for network configuration, troubleshooting, and planning. Network administrators use subnet calculations to determine available IP addresses, plan network segments, configure routers and firewalls, and troubleshoot connectivity issues. Proper subnet planning prevents IP address conflicts, enables efficient address allocation, and supports network segmentation for security. Subnet calculations are fundamental to network administration, cloud infrastructure setup, and enterprise networking. Knowing network boundaries helps you configure devices correctly and diagnose network problems effectively.
Frequently Asked Questions
What's the difference between network and broadcast addresses?
The network address (first address in subnet) identifies the subnet itself. The broadcast address (last address) is used to send data to all hosts in the subnet. Both are reserved and cannot be assigned to individual hosts.
How many usable hosts are in a subnet?
Usable hosts = 2^(host bits) - 2. The minus 2 accounts for the network and broadcast addresses. For example, a /24 subnet (8 host bits) has 2^8 - 2 = 254 usable host addresses.
Can I use CIDR notation?
Yes. CIDR notation (like 192.168.1.0/24) is commonly used and more convenient than typing full subnet masks. The number after the slash represents the network bits in the subnet mask.
Why do I need to know subnet information?
Subnet information helps you configure devices with correct IP addresses, set up routing, configure firewalls, troubleshoot connectivity issues, and plan network expansion. It's essential for proper network operation.