IP Subnet Calculator
Calculate network addresses, subnet masks, host ranges, and CIDR notation for both IPv4 and IPv6 networks. Professional networking tool for network administrators and IT professionals.
IPv4 Subnet Calculator
Calculate IPv4 subnet information including network address, broadcast address, subnet mask, and usable host range.
IPv6 Subnet Calculator
Calculate IPv6 subnet information including network address, prefix length, and address type classification.
IPv4 Subnet Reference Table
| CIDR | Subnet Mask | Usable Hosts | Class |
|---|---|---|---|
| /8 | 255.0.0.0 | 16,777,214 | Class A |
| /16 | 255.255.0.0 | 65,534 | Class B |
| /24 | 255.255.255.0 | 254 | Class C |
| /25 | 255.255.255.128 | 126 | Class C |
| /26 | 255.255.255.192 | 62 | Class C |
| /27 | 255.255.255.224 | 30 | Class C |
| /28 | 255.255.255.240 | 14 | Class C |
| /29 | 255.255.255.248 | 6 | Class C |
| /30 | 255.255.255.252 | 2 | Class C |
Understanding IP Subnetting
What is Subnetting?
Subnetting is the practice of dividing a network into smaller, more manageable sub-networks (subnets). This process helps improve network performance, security, and organization by creating logical divisions within a larger network.
IPv4 vs IPv6
IPv4 uses 32-bit addresses and supports approximately 4.3 billion unique addresses. It uses dotted decimal notation (e.g., 192.168.1.1) and subnet masks to define network boundaries.
IPv6 uses 128-bit addresses and provides virtually unlimited address space. It uses hexadecimal notation with colons (e.g., 2001:db8::1) and prefix lengths instead of subnet masks.
CIDR Notation
Classless Inter-Domain Routing (CIDR) notation is a method for describing IP addresses and their routing prefix. It's written as an IP address followed by a slash and a number (e.g., 192.168.1.0/24), where the number represents the number of bits in the network portion of the address.
Subnet Mask
A subnet mask is a 32-bit number used in IPv4 to separate the network and host portions of an IP address. It determines which part of the IP address refers to the network and which part refers to the host.
Network Classes
Class A: 1.0.0.0 to 126.255.255.255 (Large networks)
Class B: 128.0.0.0 to 191.255.255.255 (Medium networks)
Class C: 192.0.0.0 to 223.255.255.255 (Small networks)
Class D: 224.0.0.0 to 239.255.255.255 (Multicast)
Class E: 240.0.0.0 to 255.255.255.255 (Reserved)