Invalid IP address or CIDR notation.
Common notations: /24, /16, /8 or enter mask like 192.168.1.0/255.255.255.0
Quick:
Common notations: /24, /16, /8 or enter mask like 192.168.1.0/255.255.255.0
Enter an IP address with CIDR prefix (e.g. 192.168.1.0/24) or with subnet mask
Click Calculate to get network address, broadcast, host range, and subnet details
Click any value to copy it. Use quick buttons for common subnets
An IP subnet calculator helps network engineers, system administrators, and IT professionals quickly compute subnet information from an IPv4 address and CIDR prefix length. Instead of manually performing binary math, this tool instantly shows you the network address, broadcast address, usable host range, subnet mask, wildcard mask, and total number of hosts.
CIDR (Classless Inter-Domain Routing) notation like /24 tells you how many bits are used for the network portion. A /24 means 24 bits for the network and 8 bits for hosts, yielding 254 usable addresses.
Computes all subnet details in milliseconds — no page reload needed.
See IP address, subnet mask, and network in binary for deep understanding.
For smaller networks, view the first 8 subnets with their host ranges.
One-click buttons for /8, /16, /24, /28, /30, /32 — the most common sizes.
Click any result value to copy it instantly for configs or documentation.
All calculations happen locally. No data sent to any server.
Network design: Plan IP addressing schemes for office networks, data centers, or cloud VPCs. Verify your subnet size will accommodate all required hosts.
Firewall rules: Determine the exact network address and wildcard mask needed for ACL entries in router or firewall policies.
Troubleshooting: Quickly check if two IP addresses are in the same subnet, or find the correct gateway for a given host.
Cloud networking: Calculate CIDR blocks for AWS VPCs, Azure VNets, or GCP subnets to avoid overlapping address spaces.
Certification study: Visualize binary subnet math for CCNA, Network+, and other networking certifications.
CIDR (Classless Inter-Domain Routing) notation uses a slash followed by a number indicating how many bits are for the network. /24 = 24 network bits, 8 host bits, equivalent to 255.255.255.0.
Usable hosts = 2^(32 - prefix) - 2. A /24 has 2^8 - 2 = 254 usable hosts. The -2 removes the network and broadcast addresses.
The wildcard mask is the binary inverse of the subnet mask. For 255.255.255.0 the wildcard is 0.0.0.255. Used in Cisco ACLs and OSPF configurations.
RFC 1918 private ranges: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16. Not routable on the public internet.
A /30 provides only 2 usable hosts — ideal for point-to-point links between routers where you need exactly 2 IPs and want minimal waste.
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