IP / CIDR Calculator

The IP/CIDR Subnet Calculator is a free online tool that computes network details from any IPv4 address and CIDR prefix length. Enter an IP address with CIDR notation (e.g., 192.168.1.0/24) and instantly get the network address, broadcast address, subnet mask, wildcard mask, usable host range, and total number of hosts.

Understanding IP subnetting is essential for network administration, server configuration, firewall rules, and cloud infrastructure design. This subnet calculator eliminates manual binary math — just enter your CIDR notation and get all the details you need in one place.

The tool runs entirely in your browser with no server communication, making it safe for calculating production network details.

1. Enter an IP address — Type an IPv4 address with CIDR prefix, e.g., 10.0.0.0/8 or 192.168.1.100/24.
2. View network details — Instantly see network address, broadcast address, subnet mask, wildcard mask, first and last usable host, and total usable hosts.
3. Adjust the prefix length — Change the CIDR prefix (e.g., /24, /16, /8) to see how different subnet sizes affect the address range.
4. Copy results — Copy individual values or the full summary to your clipboard.

• Full subnet breakdown — Network address, broadcast, subnet mask, wildcard mask, usable host range, and host count.
• CIDR notation support — Enter addresses in standard CIDR format (e.g., 192.168.0.0/24) for instant calculation.
• Binary representation — See the binary form of IP addresses and masks for educational and debugging purposes.
• Common subnet reference — Quick reference for common CIDR prefix lengths and their corresponding subnet sizes.
• Instant calculation — Results update as you type with no loading or server round-trips.
• 100% client-side — No network data is sent to any server. Safe for production IP addresses.

• Network planning — Calculate subnet sizes when designing network architectures for offices, data centers, or cloud VPCs.
• Firewall rules — Determine the correct CIDR range for security group rules, ACLs, and firewall configurations.
• Cloud infrastructure — Plan VPC subnets, CIDR blocks, and IP address allocation for AWS, GCP, or Azure deployments.
• Troubleshooting — Verify whether two IP addresses are on the same subnet, calculate broadcast addresses, or check for overlapping ranges.
• CCNA / networking study — Practice subnetting calculations and verify answers while studying for networking certifications.